Youths broke into a derelict Letchworth industrial building yesterday and set fire to it, prompting police and firefighters to rush to the scene.

Officers were called to the old BT building in Avenue One at about 3.30pm after reports that intruders were inside.

And both engines from Baldock & Letchworth fire station rushed to the scene after smoke was seen coming from inside the building, with nobody yet seen to emerge.

Baldock fire watch commander Julian Stanley told the Comet: “A couple of youths had set a fire on the first floor. When we got there we were told that the youths had been seen in there but hadn’t been coming out.

“Fortunately they were located on the ground floor by police, and we extinguished the small fire using buckets of water on the first floor.”

Officers detained the two youths, whose fire was found to have damaged plasterboard and insultation in the building.

A police spokeswoman said that the pair had been dealt with through a community resolution, and were set to attend a fire safety course.

The long-vacant 4½-acre site in Avenue One is earmarked by developers Aberdeen Asset Management for a £16 million revamp, which includes a McDonald’s restaurant, Travelodge hotel, Aldi supermarket and drive-through café.

The mixed-use development, dubbed Letchworth Gateway, could open next year if planning permission is granted.