Media playback is unsupported on your device Media caption Aerial footage shows fire fighters tackling the blaze at a school building in Weybridge

Children and teachers were evacuated from a school after a suspected explosion caused a fire to break out.

Eyewitnesses reported hearing the blast, at St George's Junior School in Weybridge, Surrey, at about 12:35 GMT.

Shortly afterwards, huge clouds of black smoke were seen billowing up from building works on the school grounds.

All children and staff were later allowed to return inside the school, and no injuries were reported, Surrey Police said.

Image copyright @Brendan_Surrey Image caption A huge cloud of smoke was visible nearby shortly after the sound of an explosion was reported

An eye witness said he had been told there were no casualties but had seen children being evacuated.

'Black and billowing'

"I saw all of them collected together in a road behind the school there were teachers making sure they didn't go anywhere," he said.

"They were safe away from the fire. The smoke was blowing away from them."

"It was black and billowing but the fire crews are down there and they have obviously dealt with it."

Image caption The fire started in the extension being built at St George's Junior School

Image copyright Ben Scriven Image caption Eyewitnesses described seeing 'black and billowing' smoke overhead

'Returned to class'

Head teacher Antony Hudson said he was relieved there had been no casualties.

"All the children have returned to class and we very much look forward to seeing them again on Monday morning for business as usual," he said.

Surrey Police said several roads had been closed and advised motorists to avoid the area.

Parents should await further updates before attempting to collect their children, the force said.

Image caption Pupils were evacuated to the school playing fields

A spokesman for Surrey Fire and Rescue Service said 40 firefighters, eight fire engines and a number of specialist vehicles were sent to the blaze.

Area commander Ian Thomson said the roof was well alight when crews arrived.

"The fire is now under control and we are investigating the cause," he said.

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