THIRTY people had to be led to safety from an office after an explosion in Laindon.

Workers at the Essex Probation Service building had to be taken to safety after a series of exlosions near Carraway House, in Durham Road.

Two crews from Basildon fire station raced to the scene and found petrol had caught alight in nearby sewers.

Three manhole covers in the car park of Carraway House had been blown off in the blast, while a car parked over one of them suffered engine damage in the incident. A resident in nearby Bedford Road, who did not want to be named, said: “I heard a loud thud and at first thought someone had broken into my house.

“Then I heard sirens and saw the fire engines turn up.

“I’m just glad it was an accident and no one was hurt.

“You do worry living so near a probation centre what the criminals might do, and when you hear about an explosion, you certainly think the worst.”

Firefighters arrived at the scene at 4pm on Friday and found the fire had already been put out.

Gareth Critch, station officer from Basildon, said: “At first we thought it was a gas leak, but now we are 90 per cent sure it wasn’t.

“Somehow petrol entered the sewers, fumes went along the sewer drainage pipes and found their way to the boiler room in the office building.

“When it fired up, it ignited in the room.

“There was a small fire in there in what looked like a bucket.

“The flames went straight back to the drainage holes and blew the manhole covers up in the car park.

“We evacuated the building, taped the area off to make sure no one could enter the hazardous area, and waited for the gas board to arrive.”