It is feared thousands of people have died in an earthquake in Haiti. The earthquake had a magnitude of seven, and there were a number of aftershocks.
BBC News website readers have been describing how the earthquake has affected them.
SUSAN WESTWOOD, PORT AU PRINCE, HAITI
I am a paediatric nurse working for an orphanage just outside Port-au-Prince. I was in the intensive care room looking after a nine-month-old baby girl when the earthquake hit. The floor started shaking violently and the whole building shook from side to side. It lasted about 45 seconds. After that, there was a constant shuddering. The babies were really frightened and started to cry. Other staff and carers were screaming, they were so terrified. It was very upsetting.
A collapsed apartment in Cabaret, Haiti. Picture: Michael Gill
I couldn't stand upright so I dropped to my knees. I was able to keep hold of the baby girl and I grabbed hold of another baby. Objects were falling from shelves, there was debris crashing all around. I clung on to the babies and shielded them as best I could. Then came the aftershocks. It was impossible to even move.
After a while we managed to take all the children out onto the driveway. We spent the whole night outside. It was chilly but we were OK. Some children are dehydrated now though because we couldn't get any medical supplies out of the building.
Thank goodness our building is alright as is our other home up the road. I can't believe there's no damage and that we are all safe.
We have 85 children under two-years-old here at the God's Littlest Angels home. We also run another orphanage up the road. The age group there is from two to 11. There are 65 children there. All the children in our care are incredibly vulnerable.
Most of them aren't orphans but they are here because their families can't afford to look after them. Haiti is very, very poor. I see a lot of children who are malnourished. Often, it is too late by the time they come to us. Others are here because they are premature babies and we can look after them.
When I look around the area and see that other buildings have just crumbled to the ground, I know that soon we will have lots more babies and young children to care for.
EMMET MURPHY, JACMEL, HAITI
I was driving through the mountains on my way home to Jacmel when the car started to shake. It was like a very strong wind was blowing and I nearly lost control of the car. Rocks started falling on the road. I continued driving slowly and I saw people in the road screaming. The mountain was collapsing and a building to one side had already fallen down. A huge dust plume raised from the valley floor.
I drove further and found the road totally blocked by a massive landslide on the road. I just knew that if I had reached that spot five minutes earlier, I would have been killed. I had to abandon the car and continue on foot.
I run a food security project in Haiti which focuses on improved agriculture, mother and child health nutrition and early warning systems. I prepare for natural disasters but mainly for hurricanes not earthquakes! We have offices across Haiti. Our office in Jacmel seems to be intact, but there is major destruction here. My staff in Jacmel are all safe but I can't reach my people in Port au Prince.
Last night they asked all Jacmel residents to sleep on the airstrip as the aftershocks continued and there was major damage to houses in Jacmel.
CHRISTINE BLANCHARD, NEW JERSEY, USA
My family is still missing. The phone lines are down and I haven't been able to get in touch with them. I was born and raised in Haiti. My parents and I came to America a few years ago but the rest of my family, my grandparents, aunts, uncles, cousins and friends are still there.
I am using social network sites to try to track them down. I know this is how a lot of my friends have got in touch with each other. I've heard that a lot of people are at the Hotel Oloffson because it's one of the few hotels still standing. I'm in touch with people there and they will let me know if any of my family arrive.
I have been up all night trying to get in touch with people. Haiti is very small so everybody knows everybody else, I hope this will help.
It's just so awful. I feel sick with worry. I am devastated. I know every building that has collapsed. I know how long those buildings took to build and now they are just rubble.