A TEENAGER who narrowly escaped a fire while 'urban exploring' at a derelict town centre office block has warned others not to enter the death-trap building.

The 17-year-old, who asked not to be named, was one of two young men treated for shock and smoke inhalation following the blaze at St John's House, Serpentine Road, Poole.

The pair had been taking part in the urban explorer craze, which involves exploring man-made structures, often derelict buildings, and taking photographs.

St John's House, which has become a magnet for thrill-seekers and homeless people, is set for demolition.

It is also subject to a court order, prohibiting anyone from entering the structure.

The 17-year-old, who spent four hours in hospital after his ordeal, told the Echo: "We were at the top floor, then the fire started.

"We saw smoke coming up the stairs but just thought it was a homeless person doing some cooking. Then we heard sirens, looked outside and saw the fire brigade.

"But we still didn't realise it was for a fire in our building."

It was only as they both descended the stairs and saw thick, black smoke that they started to worry.

"The only way to get out was to go through the room where the fire was in, to get to the stairwell the other side," he said. "We had to crouch down because the smoke was getting lower and lower.

"Then, as soon as we opened the stairwell door it made the fire worse. We looked back at it and heard this hissing sound. Then when we made our way down the stairs we heard an explosion, like a little pop, behind us. It must have been a gas stove or something going up."

The pair were met by firefighters and other emergency services and treated for smoke inhalation and shock at the scene.

"We probably won't be doing urban exploring again," he told the Echo. "After this we're going to stay well away from buildings like that - and I'd advise other people thinking about going in there to do the same."

Six fire engines, including the aerial ladder platform, paramedics and police attended the scene around 5.30pm on Wednesday.

St John's House has been vacant for more than two years after Borough of Poole's (BOP) transportation services moved back to the Civic Centre. Developers want to build flats at the site.

Borough of Poole planning and regeneration manager Richard Genge said: "We have received a notice of intended demolition of St John’s House and resolved to grant planning permission, which includes the demolition, which will be granted once the S106 has been signed."

Currently, there is no definitive date set for demolition.