in a gas explosion in an unoccupied house in east Belfast.
Police believe that one member of the group of three girls and two boys afternoon after being caught had been handling a gas cylinder at the time.
Two girls and a boy were being treated for serious burns to the face at the Royal Victoria Hospital in Belfast last night. The injuries of the other two youths were not thought to be serious.
The impact of the blast caused the front of the building on Tildarg Street to collapse. More than 150 residents were evacuated from the area.
Chris Kerr, area commander of the Fire and Rescue Service in Belfast said last night that it was "extremely fortunate" that no lives were lost in the incident.
"The Fire and Rescue Service was called to the scene just after 3.30 pm. When the first crews arrived they found that an explosion had occurred blowing the front of the house into the street. Two girls were badly burnt and needing immediate medical attention. The first crews asked for assistance and were joined by colleagues from fire stations all over Belfast," he said.
More than 75 firefighters and police officers attended the scene, just off the Woodstock Road.
"Six pumping appliances and seven special appliances attended the scene as well as our specialist rescue team who are trained for collapse structure rescue," he said.
"We began the search of the area and found one other casualty – a man who had sustained severe burns.
"Our search dogs were then required and a specialist operation was carried out. There was a smell of gas so fire crews used hoses to ensure no further explosions took place."
Mr Kerr said he was told by the police that two other people had been injured in the blast and taken to hospital.
"Eye-witnesses told us that five people had been seen around the explosion. We carried out a search of four streets using our specialist search teams and rescue dogs and that search was found negative. Once the building where the explosion occurred was made safe our search teams re-entered it and conducted a detailed search and found nothing," he said.
"We now believe all persons involved in the incident are accounted for and we are now handing the scene across to the PSNI. At this stage there is nothing to indicate that the explosion was sinister or deliberate. However, it is under investigation and I can't confirm the source of the explosion."
Mr Kerr paid tribute to the fire crews who took part in yesterday's operation who, he said, acted with "real courage".
"It was an extremely serious incident, and although people have been injured it is extremely fortunate that no lives were lost."
Ellie Jenkin, 67, who lives six houses from where the explosion took place said the incident brought back harrowing memories of the Troubles.
"I heard this merciful bang. I thought it was a bomb and didn't know what to make of it. It shook me up terribly," she told the News Letter.
"I'm a single woman and live on my own with my cat. I was in La Mon House the night of the bomb 28 years ago. When I heard the loud bang go off today, it was the first thing I thought of. I never want to run into anything like that again. My whole body was shook up inside."
Police directed residents to the nearby Salvation Army Belfast Temple on the Cregagh Road for food and shelter if they beeded it.
But Sid Cook of the Salvation Army said many had not taken up the offer as they were concerned that their homes might be burgled.
"We were told there was an explosion on Tildarg Street. This kind of thing hasn't happened in the area in recent times but we're always on standby. We are providing food and shelter here today to residents who were evacuated from their homes," he said.
"We have also taken tea and coffee down to the front line because a lot of residents don't want to leave their homes unprotected in case someone gets in the back."