Police in Australia have launched an arson probe after four elderly people were killed and another 14 critically injured when two fires tore through a nursing home in Sydney.
Firefighters crawled through blinding smoke to rescue victims.
The blazes broke out in separate parts of the complex, and police are investigating whether they were deliberately set.
Fire Assistant Commissioner Jim Smith said sniffer dogs would search the ruins for traces of an accelerant.
A total of 88 patients were evacuated from the single-storey building in suburban Quakers Hill as firefighters searched rooms on their hands and knees for patients, many of them bedridden and suffering from dementia, Fire Commissioner Greg Mullins said.
Many of the patients were later left in the open on beds and in wheelchairs until they could be transported to alternative accommodation.
"This is a firefighter's worst nightmare," Mr Mullins said. "Turning up to a nursing home with elderly people who can't get themselves out of harm's way."
Flames raced through the ceiling, and part of the roof of a wing collapsed.
Police confirmed that three patients had died, including two whose bodies remained in the charred ruins of a room where one of the fires started. That area was too dangerous for investigators to enter.
Later, police reported a fourth death among 15 patients who had been admitted to intensive care units.
Officers said five of the 15 suffered severe burns. No staff members at the nursing home were injured.
Federal Minister for Mental Health and Ageing Mark Butler said the nursing home's fire safety systems were found to meet standards during an audit in July.
Assistant fire chief Mr Smith said the facility did not have sprinklers but was not required to by law.
"The reason there's not more fatalities is the tremendous work of the emergency workers getting there very quickly... and rescuing those patients very quickly," he said.
Neighbour Don Cook, who shares a fence with the nursing home, was among the first on the scene to see patients carried out.
"The old people, a lot of them seemed to be staring into space - they didn't know what was going on," he told Australian Broadcasting Corp radio. "To me, a lot of them looked bewildered."
Firefighters described the blaze as Sydney's worst since 16 patients died in a nursing home fire in suburban Sylvania Heights in 1981.