DOZENS of houses were evacuated and roads sealed off as emergency services battled to contain a major gas leak which caused traffic chaos for 12 hours.

Police, fire, council and Transco staff worked to contain the leak and clear the area around Blackburn Road, Darwen yesterday.

Workers used special probes to search the road for potential leaks in the pipes, and the search moved towards Blackburn Road, near to St Alban's Guest House.

A police spokesperson said the leak was located by Transco at around 8pm and is thought to have been caused by a defect in the gas pipe.

The county's joint Operation Merlin, a procedure designed to deal with incidents which lead to major disruption, was activated.

Residents from 25 houses in Blackburn Road -- the A666 -- were evacuated when the leak was reported yesterday at 11am.

Because the A666, the sliproad of the M65 and other roads were also sealed off, many residents from other streets were unable to return to their homes until around 7pm yesterday. The roads were re-opened just after 11pm.

Police set up road diversions through Earcroft and via Lower Eccleshill Road and Hollins Grove Street, with traffic stretching back for miles during rush hour.

People living in Blackburn Road were all back in their homes by midnight. Many had been to the Knott Street Community Centre where council staff had set up an evacuation centre.

Pensioner Gladys Shorrock said: "I went out at 8.15am yesterday and smelt the gas. By the time I had got back, someone had reported it.

"I was allowed into my house but told to keep the windows open which I did. Then they evacuated us all very quickly. It was all quite worrying."

Jean and Roland Grisedale, of View Road, were left stranded when police had to cordon off the only route to their home from Blackburn. Jean said: "It is very good that we could go to the evacuation centre because otherwise we would have had to sit in the car all day.

"We didn't mind because we knew what had to be done."

Divisional Officer Pete Aspden, of Lancashire Fire and Rescue, said: "This had extremely dangerous potential.

"We think that the leak happened in the pipes right where the gas is of an explosive mixture.

"Transco were running the show. I know it caused the police major problems, and we had two units standing by in case it goes off."

School children at Darwen Vale High School, St Cuthbert's CE Primary School and St Edward's RC Primary School were kept in their classrooms until arrangements could be made to take them straight home, with the last to leave at around 5pm.

Infants at St Edward's were also left disappointed after their nativity performance last night was cancelled.

A spokesperson for the school said: "The police have been very helpful, escorting some of the pupils home. Our last child was collected at 5pm, but we had parents ringing all day to find out what was going on.

"Unfortunately we had to cancel the infants' Christmas play, but we are hoping to re-schedule it for next week."

Lynne Dunning, head teacher at Darwen Vale High School, said staff were manning the phones until early evening and gave lifts home to pupils living a distance from the school.

She added: "We have been in constant touch with the police who were extremely helpful with diverting traffic and the school buses, some of which had to be cancelled.

"We are hoping everything will be back to normal today."

Richard Butler, owner of the St Alban's Guest House, Blackburn Road, said: "I wanted to go home, but there was nothing I could do. The guest house is right opposite where they were working. My dog was in there, but they wouldn't let me in.

"They said to leave the door of the guest house open, to let the fumes out. You could smell it right up the road."

Local resident Sylvester Crane, who runs the Intack Removal Company, on Blackburn Road, said: "They just turned up and said they were closing the road. They didn't know where the leak was.

"I had to close up for the day, losing a day's trade."

And Tom Henderson of Ribble Avenue said: " I was trying to get home to get changed to go to work but couldn't get my car out from where was parked."

Local hairdresser Anne-Marie Oddie, of Haircraft on Blackburn Road, said: "We've had customers phone and cancel, so it's affected our business."

But Gladys Cook, of nearby Hawkshaw Avenue, was glad something was being done. She said: "It can't be helped, can it. They have to do all this if it's gas. It's just one of those things.

"It's inconvenient but we don't want to be gassed."

Sgt Phil Houghton, of Darwen police, said: "Transco required it to be shut for safety's sake. We had contingency plans in place -- Operation Merlin. Local authorities worked with the emergency services, and found a suitable place to put people."

Chief Executive of Blackburn with Darwen Council, Phil Watson, said: "The council has supported the police and fire in their emergency procedures in several ways.

"Firstly highways officers were brought in to help with the road closures and provide information and support to the emergency services.

"Environmental health officers had to assess the risk to the environment by the leak, which they assessed as minimal, although there was a significant risk of fire.

"The council's community development staff established a rest centre for people evacuated from their homes to use should the need arise. All services have worked together well to help co-ordinate support in an emergency."