Two people have been taken to hospital - one with serious injuries.

Emergency services are warning people to stay indoors and keep their windows and doors closed.

Pictures from the scene show a three-storey block of apartments on fire, and an adjacent building has been evacuated.

A spokesperson for Bedfordshire Fire and Rescue Service said: "We are currently in attendance at a major gas explosion on Redwood Grove, Bedford.

"There are currently six appliances, two water carriers, an incident command unit at the scene. Please avoid the area and keep windows and doors closed."

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A statement from Bedfordshire Police said: "Emergency services have responded to an explosion at Redwood Grove, Bedford this morning.

"This resulted in a significant fire at a three storey block of 20 flats, which has engulfed the whole building and caused a large portion of the roof to collapse.

"There are two people who have been taken to hospital, one with serious injuries to Addenbrooke's.

"Police, fire and the ambulance service all remain in attendance."

'I witnessed someone jump from the second-floor window'

Adam Fisher, who works in a nearby building, said: "A huge explosion [was] heard - everyone went to our work car park to see what was happening.

"Our building is adjacent to the apartment complex - immediately an inferno (was) visible, huge smoke cloud billowing, people screaming and people frantically calling for emergency services."

Another witness, who did not want to be named, told PA: "I walked to town and saw the flames and also witnessed someone jump from the second-floor window whilst flames were blaring out."

Bali Mummon told Sky News: "You just kind of felt helpless at the time, thinking of the worst.

"The hope is people were not seriously injured - or even fatalities.

"And I don't know what's happened but I just hope there was hardly anyone in there."

John O'Reilly, 76, was "knocked off [his] feet" by the explosion.

He added: "There were bricks in the road so it was obviously a very large explosion to do that sort of damage."

The nearby John Bunyan Centre was was set up as an emergency assistance centre, with members of the British Red Cross present to help.