Health reporter, BBC News
Children in Haiti face are incredibly vulnerable to injury, illness and trauma
Some of the most harrowing stories coming out of the devastation in Haiti are those of children, alone, scared and severely injured.
Under-18s make up almost half of Haiti's 10-million population and aid agencies are warning they are at great risk from ongoing physical and psychological trauma.
Already the country faces the highest rates of infant and child mortality in the Western hemisphere with diarrhoea, respiratory infections, tuberculosis among the leading causes of death.
It is also estimated there are 19,000 children with HIV/Aids with few drugs available to treat them.
Unicef, which suffered heavy damage to its own offices in Port-au-Prince, says children are "tremendously vulnerable".
Gareth Owen, Save the Children's director of emergencies, said petrified children were sleeping amongst dead bodies and were in grave danger.
He estimates up to two million children could be affected by the disaster.
"Many will have been orphaned or are badly injured themselves and in urgent need of medical help."
"Thousands more will have lost all contact with their families and friends and are now struggling to survive alone in the rubble.
"They are sleeping on their own, trying to cope with the trauma of seeing dead bodies, and will have no idea where to go for help.
Bev Collin, a paediatric nurse with Médecins Sans Frontières (MSF), provided care in Indonesia after the tsunami.
She says childhood diseases already prevalent in the country will be greatly exacerbated by the devastation left by the earthquake.
"There will be a lot of dust around so the air quality will be poor which can aggravate things which are already high risk in children, such as pneumonia.
"The other things that are high risk are hepatitis A and E, typhoid fever and diarrhoeal diseases, which are made worse by lack of water.
"And food or water borne diseases will be a major problem because there is probably no drainage and sewage system."
The initial days after the earthquake will all be about survival, digging people out of the rubble and dealing with crush injuries but there are also ongoing dangers of injury from collapsing and broken buildings, she says.
"But in three or four weeks the wet season will be starting and that is really going to cause problems because then you are looking at malaria.
"Also Japanese encephalitis is endemic and is a particular problem for children."
She says aid agencies will be trying to co-ordinate who is responsible for what and getting children to a place of safety is paramount.
Those who have lost parents will usually be cared for by older siblings, other family members and the wider community, she says.
But it is absolutely vital that they can access medical facilities in the coming months.
"The thing is these are kids who are already sick and you want to be able to continue their care."
Physical wounds are of course not the only issue, there will also be psychological scars.
Professor Richard Williams, lead officer for disaster management at the Royal College of Psychiatrists, said most people, children and adults, will experience fear, anxiety, guilt, disorientation, hopelessness and other related feelings within the first few days of a disaster.
But that is usually temporary and 80% will not have lasting mental health problems.
For a small group there is a longer term risk of depression and anxiety as well as post-traumatic stress disorder.
"Children are particularly vulnerable because they depend on adults to care for them.
"If they have lost contact with familiar adults there will be the additional burden of grief and bereavement.
"It is right to focus on children but the good news is they are just as resilient as adults."
He says the psychological "first aid" that is needed is practical help and that includes food, water and shelter.
"After that it is about re-establishing normality and relationships and routine - reconnecting children with their families and getting them back to school.
"All these things are incredibly protective of mental health."