BBC reporters have been on the ground in Colombo throughout today as protesters stormed Prime Minister Ranil Wickremasinghe's office.

Here's a selection of images from the scene:

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We're hearing more reactions to the speech delivered by Prime Minister Ranil Wickremesinghe - now also Sri Lanka's acting president after being appointed by outgoing President Gotabaya Rajapaksa, who fled the country on a military jet overnight.

Sajith Premadasa, leader of the opposition, said the PM's appointment as acting president was a "farce" and "tragedy".

Premadasa added that it demonstrated the "Rajapaksa style of democracy".

Ram Manikkalingam, an adviser to Sri Lanka's former President Chandrika Kumaratunga, told the BBC he also had doubts about the appointment and his fears about the political landscape in Sri Lank were increasing.

Manikkalingam said that Sri Lanka was "facing a volatile situation where an unelected prime minister [Ranil Wickremasinghe] who could not even get elected to his own seat in parliament is now acting as if he is in charge of the country".

One protester at the prime minister's office has told the BBC that they are "still fighting, still struggling" - despite the call for co-operation from Ranil Wickremesinghe, who departing President Gotabaya Rajapaksa has named as acting in his stead.

Nixon Chandranathan said the demonstration against the government had left him "feeling great today", but he wouldn't be satisfied until there was a complete change of leadership.

“Our goal is for Gota to go home. And Ranil and other cabinet members to go home. We need truthful and honest leaders to build up Sri Lanka now,” he said.

The BBC's Rajini Vaidyanathan was inside the prime minister's office in Sri Lanka as protesters celebrated occupying it.

Waving national flags, the demonstrators defied a state of emergency and volleys of tear gas, to break through the security cordon.

As we've been reporting, President Gotabaya Rajapaksa has fled the country - while Prime Minister Ranil Wickremesinghe has been appointed acting president, according to the parliament's Speaker.

But, after only a few hours in his new role, Wickremesinghe has given Sri Lanka's military the authority to "do whatever is necessary to restore order".

One of the main demands of the protesters is that Wickremesinghe resign too.

Prime Minister Ranil Wickremesinghe has delivered a televised address in which he said he had ordered the military to "do whatever is neccessary to restore order".

He called on the protesters who have occupied his office and other state buildings to leave them and co-operate with authorities.

"We can't tear up our constitution. We can't allow fascists to take over. We must end this fascist threat to democracy," he added.

A BBC correspondent in Colombo says Wickremesinghe's latest statement could be an indication that the army is about to enforce security in the capital.

Tessa Wong
Reporting from Colombo

We are inside the building, in what appears to be a meeting room where the walls are lined with dignitaries’ pictures.

It used to host meetings attended by officials from around the world.

Now, under the warm glow of a large ornate glass chandelier, protesters stand on chairs and desks, waving the Sri Lankan flag, screaming and singing and chanting “that's what we said, don’t mess with us”.

Outside the room, a group of armed soldiers are standing by, impassively watching the protesters as they celebrate.

Other protesters lounge on sofas, and take pictures of the many photographs on the walls, which include many of the Queen and Prince Charles.

A second state television broadcast station has now gone off air.

The news comes less than an hour after the largest national broadcaster, Rupavahini, suspended operations after protesters stormed the building,

Sri Lanka's speaker of parliament has just announced that President Gotabaya Rajapaksa will make arrangements to send his official letter of resignation today.

The speaker said Rajapaksa - who is out the country - had called him and told him he would resign today – as previously promised on Saturday.

The letter of resignation would pave the way for Sri Lanka to trigger a succession plan, by allowing an interim president to step in for up to 30 days before MPs vote to elect a new leader.

Tessa Wong
Reporting from Colombo

Demonstrators who have taken over the prime minister's office have erupted in joy, taking selfies, chanting “Ranil lunatic, Gota lunatic” while banging drums and screaming.

On the second floor balcony, just above a sign saying "Prime Minister's Office", a crowd of protesters are holding the Sri Lankan flag aloft.

They are delirious with glee, managing to rip the gates open and push through a wall of soldiers - all while enduring hours of teargas.

Someone lights a flare above the balcony. The crowd erupts in cheers.

Protesters have breached the gates to the prime minister's office and are now flooding into the grounds.

The grounds are now completely overrun with joyous protesters, with crowds climbing on anything and everything they are able to get their hands on, according to the BBC's Tessa Wong, who is at the scene.

Many are standing on balconies screaming with jubilation, after an hours-long standoff with armed police officers outside the gates of the compound.

Protesters have been trying to get into the prime minister's office in Colombo, but the BBC has confirmed that Ranil Wickremesinghe is not there right now and so not in immediate danger.

He has been in hiding the last few days, since protesters burnt down his residential home. (He and his family were not there at the time).

Wickremesinghe - an ally of the Rajapaksas - is also highly unpopular among the public - who have been calling for both leaders to go.

Despite his location being unknown, he has still been issuing several orders through his office - including declaring the state of emergency and curfew orders.

He has also just been confirmed Acting President by the parliament's speaker.

Sri Lanka's national television channel Rupavihini has suspended its telecast.

Officials say engineers shut the channel down as throngs of protesters entered the state television office.

Tessa Wong
Reporting from Colombo

Protesters have ripped open the gates to the prime minister's office in Colombo, but a wall of soldiers are holding them back.

An angry face-off is taking place, as protesters shout at the soldiers not letting them in.

Standing on top of the guardhouse are soldiers with guns, but their weapons are lowered.

Protesters standing next to them are leading the crowd in chants.

The angry throngs have gathered outside the gates just hours after the prime minister's office declared a nationwide state of emergency and imposed a curfew on the western province of the island nation.

Police forces have been firing volleys of tear gas in an attempt to disperse the crowd, but demonstrators have remained defiant and vowed to keep pressing on.

The police have fired tear gas canisters extremely high. Streaks of smoke are arcing across the blue sky. At this height they have become dangerous projectiles as they land. Everyone's running for cover in smoke.

We saw one person hit on shoulder by flying debris falling from a great height.

In response, people are using traffic cones to scoop up tear gas canisters and are lobbing them back to soldiers.

If you're joining us now, welcome.

It's just past 1:30pm in Sri Lanka, on the day President Rajapaksa was expected to formally resign:

• Overnight, he fled to the Maldives - the island chain neighbouring Sri Lanka - on a military jet and hasn't been heard from since
• He had pledged to stand down on Wednesday amid mass protests over the island's worst economic crisis in decades

• The prime minister, Ranil Wickremesinghe, has now been appointed Acting President
• He earlier declared a national state of emergency and a regional curfew as protests picked up in the capital Colombo and elsewhere
• Many protesters also don't want Wickremesinghe in office - having called for both leaders to resign

• Big crowds of protesters are attempting to break into the Prime Minister's office, but troops are driving them back
• Soldiers had earlier fired volleys of teargas on protesters, some of whom were seen escaping the plumes while coughing and sputtering

This is Yvette Tan, Frances Mao and Zubaidah Abdul-Jalil reporting from Singapore, with our team of BBC journalists Tessa Wong, Anbarasan Ethirajan and Rajini Vaidyanathan reporting out of Colombo

Prime Minister Ranil Wickremesinghe has just been appointed Acting President, according to the parliament's speaker.

That official says President Gotabaya Rajapaksa informed him of the appointment under Article 37.1 of Sri Lanka's constitution. However there remains no direct word from Rajapaksa himself.

All announcements in recent days have come from the parliament speaker and the prime minister's office.

Tessa Wong
Reporting from Colombo

Police have fired more volleys of teargas on the crowd outside the prime minister's office in a bid to drive them back.

The avenue is wreathed in smoke. People are running, trying to escape the gas. Those hit are dousing themselves with water and coughing.

Soldiers are still holding down the fort. Perched on the building's gates, they're even dumping water on protesters to help those struggling to breathe.

As we reported earlier, police fired several volleys of tear gas on protesters, many of whom are now gathered outside the gates of the Prime Minister's Office in Colombo.

Footage from the scene shows the avenue wreathed in smoke as people run to escape the plumes while coughing and sputtering.

Some drenched themselves in water and made makeshift masks by tying bandannas over their noses and mouths to mitigate the effects of the gas.

Andrew Clarance
Reporting from Colombo

Sri Lankan protesters are staying defiant in the face of a nation-wide curfew imposed by the prime minister's office.

"Our country is facing an extreme economic crisis," 31-year-old protester Viraga Perera told the BBC.

"The people here are here so they can have a vote for the future," he said from Galle Face Green, which has been the site of multiple mass protests against the Rajapaksa administration.

"This kind of behaviour, of sending helicopters that are armed around the people who are gathered here peacefully, sends a clear signal to deter peaceful protests against the current regime," he said, referring to the military helicopters that have been flying low over the heads of protesters gathered there.

"We will not stand by this," he said.

"We will keep coming, we will keep fighting until we have some assurance that we and our children have some future in this country."

Tessa Wong
Reporting from Colombo

Intense protest scenes are taking place in front of the prime minister's office.

People have completely swarmed the gates to the office grounds, with some attempting to break down the gates themselves - swinging it back and forth on its hinges.

Others are throwing bottles at security, while police are just standing by and watching.

The building has heavy security though; a line of soldiers are guarding the perimeter.

However the crowd is just getting bigger and more riled up.

Tessa Wong
Reporting from Colombo

Thousands of people are walking along Rajikeeya Mawatha Road, near the prime minister's office and towards parliament.

Some in the crowd have been targeted with tear gas by police.

A helicopter is overhead and every time it passes over the crowd, people jeer and shout, howling angrily and showing middle fingers.