Investigators are continuing to search the remains of the 14th floor of a tower block where two firemen died trying to rescue a woman from a blaze.
Three people died in the fire at Harrow Court in Stevenage
Michael Millar, 26, of Stevenage, and Jeff Wornham, 28, of Royston - both in Hertfordshire - died in the fire at Harrow Court, Silam Road, Stevenage.
A woman who also died in the fire on Wednesday has not yet been named.
Seven other people were taken to hospital. One of those is said to be in a critical condition.
About 70 people were cleared from the building, a spokesman for Hertfordshire Police said.
The fire started in a flat on the 14th floor at about 0300 GMT and quickly spread to the floor above.
Roy Wilsher, deputy chief fire officer with Hertfordshire Fire and Rescue Service, said the tragedy had caused "deep shock for the fire service".
"We know one person escaped and our firefighters knew there was somebody else in there," he said.
"They were trying to rescue that person when that tragic event occurred.
"This is the worst day for Hertfordshire Fire and Rescue Service for 30 years. That was the last time we lost members of the service in a fire."
Mr Wilsher said the service was providing counselling for the family of the dead firefighters and their colleagues.
A family of four were among the seven people taken to hospital following the fire.
An ambulance spokesman said two adults and two children were treated for smoke inhalation before being discharged from the Lister Hospital in Stevenage.
One man was in a critical condition in the Queen Elizabeth II Hospital in Welwyn Garden City with severe breathing problems.
Another man was in the Lister Hospital with minor facial injuries.
Gary Sanderson, communications manager for Bedfordshire and Hertfordshire Ambulance Service, said paramedics fought to save one of the firefighters on the way to the hospital.
His colleague was pronounced dead at the scene.
Robert Brown, who is disabled by arthritis, was rescued from his 16th floor flat by firefighters.
He had been on the phone to the brigade when an axe came through his front door as crews rescued residents.
The 54-year-old said: "When I smelt smoke I thought I'd left my meal on but then I thought 'I haven't cooked anything'. That's when I woke up and thought I'd better do something.
"I was talking to a girl (on the phone) and she said go down the stairs and I said I can't, I have arthritis. The next thing a big axe came through the door."
Residents and relatives left bouquets of flowers outside the flats for the three people who died.
One bouquet read: "To the brave firefighters who tragically lost their lives - we salute your bravery and honour!"
Fire Brigades Union (FBU) leader Andy Gilchrist said later: "Such tragedies are felt very deeply across the entire UK fire service. It sounds old fashioned but we all hurt at times like this."
Between 1995 and 2004 nine firefighters were killed in action, from 1985 to 1994 14 were killed and another 22 died from 1977 to 1984, the FBU said.