Press Association reporter Ryan Hooper says police are advising people who live within the London Bridge cordon to stay somewhere else tonight if they can.

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Will Orton was at a pub nearby when the incident happened.

The 25-year-old said: "Lots of people came running inside, we didn't really know what was going on.

"We thought maybe there was a fight or something outside. And then there were almost hundreds of people coming inside.

"The bouncers did a really good job, they shut the doors and locked everyone in," he added.

"There was panic - it seemed like it was literally outside the door.

"People were coming inside and saying they had witnessed people being stabbed.

"It seemed like it was happening immediately outside the entrance."

People who live near to London Bridge have taken to Twitter to share offers of help to those affected by tonight's incident.

Police are now searching for three suspects, a BBC reporter at the scene says.

He says there are also reports that some people have been stabbed.

The priority for the police is now to get people - many whom where enjoying a nightout in central London - out of the area.

The police cordon is being moved further and further out, our reporter adds.

A Downing Street spokesman said: "The prime minister is in contact with officials and is being regularly updated on the incident at London Bridge."

British Transport Police have said there are a number of casualties due to the incident possibly involving a vehicle and a knife in London Bridge.

Eyewitness Samantha Wilde tells the BBC she's seen between 30 and 40 ambulances at the scene and armed police.

Earlier, there were reports of gunfire.

Image source, PA

Police are reported to be treating injured people and carrying them away at the end Thrale Street, near London Bridge.

Members of the public were told by police to "run as fast as they could" westbound.

Nick Archer, who was in the London Bridge area, told Sky News: "We came out (of a bar) on to the road and looked and looked to my left and there is a guy, I thought he was just drinking but he was lying on the floor.

"And then a couple of seconds later, about three police vans flew past. "He looked in a bad way."

Met Police have also sent armed officers to an incident at Borough Market.

Press Association reporter Ryan Hooper says the incident is affecting underground stations multiple stops down the line from London Bridge.

The BBC's Chris Wimpress at the scene says he's seen crowds fleeing the scene, many in tears as they couldn't get hold of their friends after the incident.

They were running, terrified, our reporter says.

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The BBC's Holly Jones spoke to a French woman who had been injured in the incident.

She told Ms Jones: "I don't know where those other two people are. So the police are checking the Thames.

"They were right near the edge of the bridge. It looks potentially they could have been thrown over."

Mayor of London Sadiq Khan is asking people to follow advice and information from official sources including the Metropolitan Police.

First pictures are starting to emerge from the scene.

Here, people are seen fleeing the area on Borough High Street.

Image source, PA

BBC reporter Holly Jones, who was on the bridge at the time of the incident, said the van was driven by a man and was "probably travelling at about 50 miles an hour".

About five people were being treated for injuries after the vehicle mounted the pavement and hit them, she said.

She said the van, which was travelling from the direction of central London, headed towards the south side of the river.

Ms Jones later reported seeing a man being arrested by police. She said he was handcuffed and had his shirt off.