Dr Mark Nelson from HCJB Global attends to a patient
A strong aftershock has rocked Haiti, sending screaming people running into the streets, eight days after another quake devastated the country.
Aid workers involved in the operation have been sharing their accounts with the BBC News website.
STUART COLES, PLAN INTERNATIONAL
We get an unscheduled tectonic alarm call - a groaning, gut-shaking rumble is all around us. I am half-awake, thinking about the day's plans. The earth is shifting under my feet.
I leap up, alarm shouts of my colleagues in numerous languages around me, but they are only shapes in the half light, and I can't find my glasses.
The roof groans and rattles, and things fall in the dark.
Stuart Coles is in Haiti with children's charity Plan International
My heart has jump started, and my legs propel me forward. But my brain, says "head under the desk."
Two years of living in Japan and numerous drills have conditioned me that this is what to do.
I shout my colleague Shona's name, but she is up and running from the mattress next to me. Shapes flee towards the door, light and the open.
I switch direction and follow them. Suddenly I fall and am slap down on the concrete, a stinging pain on both knees. I'm up again, running barefoot across the concrete and into the yard where the cooks work. There is a circle of us now gathered, panting. We all check everyone is out. We are.
The shaking stops. Slowly my heart slows. I look down - I am in my underwear and for some unknown reason, still clutching a pillow. Shona seems to have dragged most her bedding with her, others the same.
Deep breathing and some swearing switches to nervous giggling as we look around and realise we are all in our nightwear and holding random items.
"I've seen loads of Plan staff in their boxers," says Shona casually.
And then bizarrely laughter, relief and a touch of hysteria evident as the adrenalin works its way out. This passes, and then we come down. The reality of what has happened sinks in.
I have experienced small quakes in southern Japan and an aftershock in Banda Aceh - but this was the worst yet.
We are shaken, but not stirred.
Media calls start, they are getting news that it is a 6.1 quake - the strongest since last week's.
The team steel themselves and we prepare for Port-au-Prince.
MARTIN HARRISON, WATER ENGINEER, HCJB GLOBAL
Dr Eckehart Wolfe tends to the patient he gave blood to during an operation. Photo: Martin Harrison
A strong aftershock at 0605 local time this morning sent panic through the hospital. It is one week since the earthquake struck the Caribbean island of Haiti.
If there are two words which summarise what I have seen and experienced since I arrived here last Friday, they are "resilience" and "improvisation".
I marvel at the Haitian people as they make life continue against all odds. At the Baptist Haiti Mission Hospital where I am based many staff have lost family members and close friends, yet they have not downed tools since the first day as they seek to help others live.
The emergency response team demonstrates equally remarkable resilience and improvisation. One of the HCJB Global surgeons even gave his own blood during the middle of an operation he himself was performing to save the life of a woman with severe internal bleeding.
We urgently require stocks of blood. The hospital does not have any at all. The woman died later because there was no blood for the transfusion.
The hospital is home to two of only five hospital-based operating theatres that remain operational in Port-au-Prince. Since yesterday, we have started receiving emergency cases from refugee camps set up by the US military.
Certain essential supplies have run out such as plates for mending fractures and crutches. We urgently await their arrival. Surgeons are improvising by cutting pins in half to make them go further as they operate on many fractured limbs. Some patients are still waiting for essential operations one week after the earthquake.
There is growing concern about the spread of disease. Few of the patients have been vaccinated against tetanus and we desperately need vaccinations.
SARAH GILLAM, ACTION AID
Sarah Gillam: "Water is plentiful in Mariani but it's not potable"
I woke up this morning to hear people screaming outside and my bed shaking. Should I run outside naked or find my clothes? I opted for the clothes but realised those vital seconds could be a matter of life and death. The earth seemed to settle and after hanging around for a while, we went back inside.
In the Mariani neighbourhood of Port-au-Prince where we work, primary needs identified so far are food, shelter, chlorine tablets for water and medical attention.
We piloted our food distribution two days ago and it all went well thanks to a local donation of high protein food for children made by SCMS - an international NGO distributing pharmaceutical products for HIV patients.
I woke up this morning to hear people screaming and my bed shaking
We're confident the local committees have the capacity to distribute large quantities of food and we're taking measures to guard against any kind of hoarding and prejudice against women and children.
We have bought several tonnes of food from the Dominican Republic for distribution tomorrow. We will also be exploring local food sources from small farmers' cooperatives outside Port-au-Prince so that aid efforts don't damage local prices over the coming months.
In Mariani, water is plentiful but it's not potable. Instead of giving out water bottles, we will be giving out chlorine tablets to prevent more rubbish accumulating in the capital.
Although ActionAid doesn't normally work in the field of medicine, lots of people are dying due to lack of medical care. Many are dying from simple wounds which have become septic or gangrenous and there is a lack of antibiotics, bandages, syringes and plaster for castes.
Red Cross and ActionAid have begun talks on how they can work together through the voluntary committees which have sprung up inside the camps to guarantee medical attention.
Women and children's safety is also a serious concern. We have already started working with psychiatric professionals to develop a mid-term plan for treating post traumatic stress among women and children in the refugee camps.
DAVID DARG, OPERATION BLESSING
I have been spending my nights in an aircraft hangar for almost a full week now and have got used to the constant roar of engines from the huge cargo planes constantly taking-off and landing.
But this morning I was jolted awake by the sound of the entire hangar rattling and groaning - it was an earthquake.
Just as I made it outside the earth stopped shaking and there was quiet. The fear was evident when we arrived at the national hospital.
Operation Blessing is installing 10 water purification units in Haiti
During the quake all the patients were evacuated and none of them wanted to go back inside.
So the narrow lanes in the hospital were crammed with patients and doctors under the blazing sun.
We saw operations taking place in the open air while cars spewed exhaust fumes across the procedure. Dead bodies pulled from rubble near the hospital were wheeled to the morgue past lines of patients.
Operation Blessing installed a large water purification unit in the hospital, put in a line with a tap and provided clean water to serve the 3,000 patients and medical staff on the compound.
Tomorrow we will be installing another unit at the soccer stadium where we set up our field hospital.
The hospital now has teams of French and US doctors working alongside our Israeli team.
ISABELLE JEANSON, MEDECINS SANS FRONTIERES
I had the scare of my life this morning. I had hoped I could sleep-in an extra 10 minutes because I've been working on five hours sleep a night for the last week and am hitting the bottom of the barrel.
No such luck. I suddenly felt my sleeping bag on the bedroom floor rocking back and forth. For about a second I thought maybe I was dizzy from being tired.
But that thought didn't last long when the rocking got stronger.
I jumped up, scrambled to the door in the dim morning light in my pyjamas and ran downstairs.
I was shaking and on the verge of crying, and so was my colleague. He had survived the quake last week, but he still had the courage to run back inside the house to get our two other colleagues out.
Isabelle Jeanson: "It hurts to see so many injured children and adults."
My heart was racing. I finally understood the meaning of vulnerable, to be so exposed to this overwhelming force.
That was the start to this day. This afternoon I spent a few hours at our field hospital in Carrefour.
The entrance is through grey thick plastic sheeting, which is attached to two trees, spanning across a street in the middle of the town. This is the triage area, a wound-dressing area, and an inpatient ward.
It hurts to see so many injured children and adults, some screaming in pain as their dressing gets changed by a nurse. They have serious burns, wounds that are infected, broken arms, deep cuts in the skull, gangrened limbs, and the list goes on.
There are pregnant women who are giving birth, or who need c-sections and beds for more serious surgery, such as amputations.
In the five hours I was there, the team did at least three amputations, two for young children. They removed necrotic tissue on a young woman's thigh, and did a c-section.
Our team is tired. They have been working long, long hours in the heat, in crowded, noisy, demanding and stressful conditions. Fortunately, we've located a brand new spacious school building that was not affected by the earthquake, just down the street from our hospital.
We hope to move to this new location in the coming days.
The one shining light in all this physical and emotional suffering is the birth of healthy little babies. Eight healthy little new ones arrived today under the blue tarp of our hospital. We all need them to breathe new life and hope into this torn country.