A criminal investigation will begin today to track down arsonists who endangered people's lives and led to the evacuation of a street.

Four firefighters were thrown through the air as gas cylinders blew up, hurling debris 30ft into the sky.

A propane gas cylinder crashed through the window of the sun lounge of a house.

The couple who lived in the house had a narrow escape.

Fire Station Officer Neil Rowland said the fire and explosions on allotments off Thornhill Gardens, Hartlepool, could have had fatal consequences

"Because of these cretins, we could have had people killed," said Mr Rowland.

He was blown off a ladder by the main explosion, while directing operations to put out a fire which had taken hold in two buildings - a workshop, containing a variety of gas cylinders and an allotment shed.

Two of his colleagues suffered minor damage to their ears and a third received a back injury as all four were caught in a pressure wave generated when the cylinders exploded.

Eyewitness father-of-four James Booth said: "Luckily, I have never seen a bomb go off, but I reckon this would have been close. There was a tremendous explosion and then a big fireball."

Neighour Phillip Hope had been asked by firefighters to move his car when the cylinders exploded.

"All of a sudden, there was a bang and a column of flames which went about 30ft in the air. Everyone ran, but I just hit the deck.''

Thirty-five houses were evacuated as firefighters began a 24-hour operation to keep the oxyacetylene cylinders doused. They remained cordoned off last night, following Sunday night's fire.

Mr Rowland said: "There was a lot of flame impingement on the cylinders. We have gas experts coming down.

"When we arrived, there was a severe fire and smoke was about 60ft in the air. A propane cylinder exploded, hit a garage wall and bounced through a window.''

Firefighters were told two youths were seen running from the scene, but neighbours told The Northern Echo they had reported to Cleveland Police seeing four "undesirables" getting out of a silver-coloured Ford Sierra at about the time of Sunday night's fire.

Mr Rowland said: "It is bad enough when they set fire to people's property, but when they endanger the lives of the public and firefighters, it is deplorable.''

He said it was a miracle that one resident was not killed when a 54kg propane gas cylinder crashed through the window of his sun lounge.

Only minutes earlier, the same resident was asked by a firefighter to move inside his home for his own safety after he was spotted watching the drama from his back garden.

Two oxygen cylinders also exploded and an acetylene cylinder remained unstable.

Cleveland Police and Fire Brigade investigators will today sift through the debris of the shattered workshop and allotment shed to discover how the fire started, while detectives at Hartlepool continue the search for those responsible.