Five men were killed when an explosion tore through a building used to make illegal vodka, it has been reported.

The explosion in a building on Broadfield Lane Industrial Estate in Boston, Lincolnshire, was heard from five miles away. The industrial unit is thought to have been being used to make illegal vodka.

Emergency services were called to the scene when neighbours saw thick black smoke emerging from the estate at 7pm on Wednesday, but, according to police, the five men died instantly in the explosion.

Witnesses reported seeing a man run out of the unit with his arm on fire.

A sixth man has been injured and was taken to Queen's Medical Centre in Nottingham.

According to locals, the men were thought to be migrant workers operating an illegal vodka distillery.

A police spokesperson said it was not yet clear what had caused the fireball but that five men were confirmed dead.

"The circumstances at the moment are still unclear. There will be a full forensic examination of the unit."

Lincolnshire Fire and Rescue area manager Steve Moore said: "The first crews arrived and found a very, very hot fire and one casualty outside the building suffering from burns.

It was a very hot, very intensive fire, so much so that the steel roller-shutters were buckled."

One local said: "I heard a huge bang just after 7pm. It sounded like the world was coming to an end.

"Then it went crazy – there were firemen and ambulances everywhere.”

Police said they understood the explosion was a rapid blast as opposed to a fire.

A full forensic search will take place.