Paramedics across Ireland have been warned to check oxygen tanks in ambulances after an explosion killed an elderly patient.
Health chiefs ordered the precaution after the blast caused the vehicle to burst into into flames as the man was being taken to the emergency unit at Naas General Hospital in Co Kildare.
Two paramedics were injured trying to save the patient, aged about 70, from the back of the ambulance.
One of the men was said to have up to 70% burns but health chiefs later said he had minor injuries and was being treated in a specialist unit in St James' Hospital Dublin.
The other paramedic was discharged from hospital after a few hours.
Union representatives said the two men tried to rescue the patient as the ambulance burst into flames.
"The Health Service Executive (HSE) would like to acknowledge the heroic efforts of our paramedic colleagues and hospital staff in attempting to save the life of the deceased," the agency said in a statement.
HSE director general Tony O'Brien and other senior staff met the dead man's relatives to offer their sympathies.
The definitive cause of the explosion is not known but the agency said early indications suggest that an oxygen tank exploded and caused a fire in the rear of the one-year-old ambulance.
It is not thought to have been sparked by an engine malfunction.
"While the results of the full investigations are awaited, it would appear that the explosion was related to oxygen," the HSE said.
The blaze happened at about 1.30pm and witnesses reported hearing a loud bang.
Siptu organiser Paul Bell said: "Both of them tried to get the patient out.
"We are convinced that the paramedic crew attempted everything possible to contain the situation and save the patient. They did their duty."
Other medics and ambulance staff at the hospital are understood to have reported that one of the paramedics was in the back of the vehicle trying to get the patient out when he suffered severe burns and his colleague went in to rescue him.
Witness Rob Moore was inside the hospital when the fire alarm sounded and rushed out after hearing a bang.
"I don't know what actually happened, but the whole thing just went up," he said.
"As I came out of the door of the hospital I could see two paramedics at the back (of the ambulance), one of them was really severely burnt.
"I think there was a fireman there, who was off-duty, he started to get things under control.
"Everyone was pulled away from it then."
Mr Moore said he did not hear an explosion but believed he heard a bang or a thud.
He also saw someone he believed to be one of the paramedics being taken to an area outside the hospital, where medics stripped him down to treat his wounds.
The casualty department was shut down following the incident.
The National Ambulance Service issued an immediate safety notice for all oxygen to be checked.
The HSE's oxygen supplier has also been asked to check its products and paramedics have been asked to re-familiarise themselves with the emergency evacuation.
Several investigations have been launched including by the HSE, Fire Service, Garda and Health and Safety Authority.
Ambulances normally carry up to six sealed cylinders of different types of potentially flammable gas to treat patients.
They carry oxygen and also an analgesic gas and air mix for pain relief.
Michael Dixon, chairman of the National Ambulance Service Representative Association (NASRA), offered condolences to those caught up in the incident.
"Our thoughts and prayers are with the man who lost his life in the back of the ambulance," he said.
"But we are also concerned for the two paramedics injured as well."
Mr Bell added: "We would like to express our deepest sympathy with the family of the patient who died and our grave concern for the two paramedics who tried in vain to save his life.
"This tragedy should never have happened."