A major earthquake has struck eastern Nepal, the second one in two weeks.
The US Geological Survey says Tuesday's quake has a magnitude of 7.3.
At least 29 people have been killed and 1,006 injured in Nepal, officials say.
More than 8,000 people were killed in the first, devastating quake on 25 April.
Dr Nabin Sinjali from Ramechhap, Nepal, sent us a WhatsApp message: "I am a medical doctor working in one of the remote district of quake-hit areas of Nepal. I was examining an older patient during today's tremor when everyone in our hospital started to cry and ran out as soon as possible. We are outside now in open space. There are still small tremors. We are frightened!!!"
FlightRadar24 tweets, external: Flights are landing and taking off from Kathmandu Airport again after earlier closure due to earthquake.
Image source, Alexia McKenneyAlexia McKenney sent the BBC this photo of a fallen building and crowds of people standing in a road shortly after the earthquake.
@Pukukarki tweets:, external Praying for my home country #Nepal from so far away in #Australia @JulieEMcKay @UNWomenAust
Image source, Kunda DixitNepali Times editor Kunda Dixit tweets, external: "This 4-story block went down in Kathmandu, pedestrians thought to be underneath."
Abhaya in Nepal felt the earthquake: "I was in my room. It went on for 30 to 40 seconds. Mum and I ran outside. It was scary. Everyone came out of their houses. There was a big aftershock. Tremors are still happening now. I'm back in my house and I'm safe now."
WhatsApp user: "Hello. Today's earthquake was felt in Kolkata too. People panicked. No damage or loss in this area. Buildings were evacuated for some minutes until normality returned."
Kathmandu airport has been closed, the AFP news agency reports.
Simon Cox, Kathmandu
BBC News
"The birds started squawking and swirling around. People were all out on the streets. The aftershock caused anxiety and panic and people started crying."
After the progress that has been made since 25 April, this "re-sets everything back to day one".
Bheshraj Devkota in Nepal says: "I am safe here, but I feel terrified. I felt this quake harder than the previous quakes. Maybe this is because we are feeling the hit psychologically after having experienced the quake before. There are around 1,000 people near me. My hometown is Chitwan, the central region. I'm worried about my family members. I have called and texted them, but haven't heard anything back."
Gemma Gillie from Save the Children in Kathmandu
tells the BBC the quake felt like it "went on forever". She said everyone ran onto the roof of the building she was in, as they have in recent days because of aftershocks.
"We realised it was much stronger than anything we've had since 25 April. It was pretty terrifying.
"People had just started to feel safe. People are too terrified to go inside now."
"I can't begin to imagine how the Nepalese people have been affected by this," she added.
Image source, EPAPeople in Kathmandu ran into open spaces when they felt the tremors from Tuesday's quake. Many had been so fearful of aftershocks they slept outside for days after the last quake on 25 April.
Simon Cox, Kathmandu
BBC News
There are a lot of search-and-rescue teams still in the Nepalese capital, Kathmandu, who will be on hand to help.
Norway's Red Cross says there have been "many injured, several killed''. Medical staff have been helping at a 60-bed hospital in Chautara in central Nepal since 25 April. The hospital has already received new patients.
Bibek Chalise, Gaindakot, Nawalparasi, emailed the BBC to say: This earthquake was terrifying. I was at my school, the entire school started shaking. It was long, devastating and dangerous. Thank god that no one was hurt badly at my place.
Kashish Das Shrestha tweets, external: Like April 25, damages and losses will be significantly severe outside of KTM city. Already reports of landslides and fatalities coming in.
Biut Raj Thapa tweets, external: I am at Chitwan right now, south of Kathmandu where there is almost zero damage. But everyone is in fear & "mental quake".
Sanjoy Majumder
BBC News, Delhi
The earthquake was felt in the Indian capital. Shaking of nearly half a minute sent people panicking onto the streets in Nepal. The epicentre of this quake is much closer to Everest, but the previous quake brought the climbing season to a close so at least, for the time being, there are no trekkers.
Unicef's Rose Foley tweets, external: Strong quake. We sheltered under tables as building shook. Felt like walking on deck of boat as we made way to safety #NepalEarthquake