Eyewitnesses have spoken of scenes of devastation after a 7.0-magnitude earthquake rocked Haiti, toppling buildings in and around the capital, Port-au-Prince.
People rushed into the streets after the earthquake hit
Reuters reporter Joseph Guyler Delva said when the quake hit the city "everything started shaking, people were screaming, houses started collapsing".
Mr Delva said he had seen dozens of casualties. "I saw people under the rubble, and people killed. People were screaming 'Jesus, Jesus' and running in all directions." He described the scene as one of total chaos.
Ian Rodgers, an Australian working with Save the Children in Port-au-Prince, said people were searching for loved one in the debris.
"You are hearing the grief of people as they realise they've lost people, they can't find their children," he told Reuters.
"But then again you are still hearing these cries coming out, people who are rescuing other people from the rubble as somebody comes out alive."
Mr Rodgers said rescuers were trying to find vehicles to evacuate injured people but the city's power and infrastructure were all down, leaving it "very, very dark".
There have been few reports from outside the capital, but Global Orphan Project posted a video on the YouTube website it said had been filmed in the south of Haiti "a long way from ground zero".
The video showed what appeared to be collapsed buildings and people walking around streets strewn with debris.
'Running and screaming'
Henry Bahn, an official for the US Agriculture Department visiting Haiti, said everybody there was "just totally freaked out and shaken", the Associated Press news agency reported.
He said he was walking to his hotel when the ground began to shake. "I could hear a tremendous amount of noise and shouting and screaming in the distance."
Mr Bahn described seeing a ravine where several houses had been standing. "It's just full of collapsed walls and rubble and barbed wire."
Writing on Twitter, Troy Livesay - a Christian missionary working in Port-au-Prince - described seeing bodies in the street that had been pulled out of collapsed buildings and people standing around in a state of shock.
The capital had "always looked a little rough around the edges, so driving around at night it seems hard to see the damage, then you come upon huge piles of rubble where a supermarket used to be", he said.
Several people spoke of hearing people screaming across the city following the quake followed by singing and prayers later on.
Mr Livesay said it was "a beautiful sound in the middle of a horrible tragedy".
A user of the social networking website Twitter, identifying himself as RAMhaiti, said the singing had become "louder and more emotional" before subsiding.
He said he could hear no ambulances or helicopters and that aftershocks were still causing panic.
"People are screaming and freaking out down towards the stadium," he said.
Valerie Moliere, 15, had to be helped out of her family's home by her father and said the scene was one of confusion and anguish.
She said people were in the streets "hugging and crying" and the damage was substantial.
"I see broken houses and many people are walking in front of me and they have blood all over them," she said.
The passengers of a flight from Haiti to Miami, which left shortly after the quake hit, said the airport building had been severely damaged.
"The whole outside had deteriorated, from top to bottom it was cracked up totally," one man told reporters.
"We thought it was something that hit the building, but it turned out it was an earthquake."
Other passengers spoke of their fears for family members left behind in Haiti.
Cries for help
Carel Pedre, a TV and radio presenter in Port-au-Prince, told the BBC he had witnessed extensive damage on his five-mile walk through the city to reach his daughter.
"I saw a lot of people crying for help, a lot of buildings collapsed, a lot of car damage, a lot of people without help, people bleeding."
He said he had seen a cinema, a supermarket, a cybercafe and an apartment building, all of which had crumbled in the quake.
Mr Pedre said he could feel aftershocks every 15 to 20 minutes, lasting from three to five seconds each. The darkness, he said, was compounding the fear and worry people were feeling.
"There is no electricity, all the phone networks are down, so there's no way that people can get in touch with their family and friends," he said.
He said he had not seen any emergency services, adding that while people in the neighbourhood were trying to help each other, they did not know "where to go or where to start".
Within minutes of the quake, a huge plume of dust and smoke was seen rising from the capital.
Mike Godfrey, a contractor for the US Agency for International Development, told CNN it looked like "a blanket that completely covered the city and obscured it for about 20 minutes".