Two police officers have been injured in a blast during a siege at a block of flats.
The building in Church Square, Lenton, Nottingham, was evacuated after a man barricaded himself in a first-floor flat and threatened to cause an explosion.
Nottinghamshire Police said two officers were injured after a "detonation".
A police spokeswoman said two officers were taken by ambulance to Nottingham's Queen's Medical Centre for treatment for smoke inhalation and shock.
The explosion caused part of the building to catch fire and an outer wall to collapse. A man was arrested at the scene.
Fire crews were called to the scene as well as engineers from gas pipeline firm Transco.
The police spokeswoman added that a structural engineer would inspect the property before residents were allowed to return.
Nottinghamshire Fire Brigade attended the scene with three fire engines.
A spokeswoman said the fire was a gas explosion in a first-floor flat and four firefighters in breathing apparatus tackled and extinguished the blaze.
