At least 70 people are feared dead and hundreds injured in a huge explosion at a Texas fertiliser plant, according to the fire department.

Local news station KWTX said the blast occurred around 7.50pm local time, 12.50am GMT, at the fertiliser plant near Waco, in central Texas.

A spokesperson for the Texas Department of Public Safety, D L Wilson, said initial inspection suggested that the explosion had resulted in "probably hundreds of casualties".

The cause of the blast is not yet known.

The explosion has reportedly destroyed several buildings in the vicinity of the factory, including a nursing home, trapping the residents. Local volunteer firefighter James Miller said they were trying to evacuate those inside.

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County Sheriff Parnell McNamara likened the explosion site to a "war zone".

"It's a lot of devastation. I've never seen anything like this," he told Reuters.

A spokesperson of the public safety department told the media that rescue officers have transported more than 100 injured people in their patrol cars to Hillcrest Baptist Medical Centre in Waco. She also confirmed the deployment of six helicopters to aid the rescue team at the blast site.

The West Independent School posted on Twitter that residents were being asked to evacuate the area till the fire was doused.