A BLAST in a furnace at a marine supplies works left four people injured as molten metal sprayed across the factory floor.

Yesterday's explosion sent the blazing hot contents of the furnace blasting out across a 20 square metre area – leaving two men seriously burned and two more with minor burn injuries.

Flames spread after the explosion at Teignbridge Propellers on the Brunel Industrial Estate in Newton Abbot.

An investigation has been launched into the incident at the factory, which is a leading worldwide supplier of propellers and stern gear for the boatbuilding industry.

Inspectors from the Health and Safety Executive were at the site last night in the wake of the blast, which witnesses described as "louder than a gunshot".

Acrid black smoke hung over the town after the explosion.

Police set up a 300-metre exclusion zone around Forde Road and the factory after the incident.

An aluminium bronze rudder being smelted in one of the firm's seven furnaces sparked the explosion just after 8.30am. The smoke could be seen for miles around and police maintained the cordon until the threat of exploding acetylene cylinders had been removed.

Staff at the factory, which employs about 85 people, were evacuated.

One man, who was sprayed with molten metal, was taken to hospital suffering from burns.

Three others were also treated at the scene for burns and were taken to Torbay Hospital for further treatment.

None of the men were believed to have suffered life-threatening injuries.

Windows at the factory were blown out and blackened after the fire, which saw crews from Newton Abbot, Torquay and Totnes called in to tackle it.

Teignbridge Propellers director David Hunt said staff were sent into town as fire crews worked.

He said the fire had been in a contained area. Only one bay needed cleaning up, he said, and the factory and other areas would quickly be back to running at 100 per cent.

He added: "It looked like the fire was gathering pace, and there was lots of smoke."

A spokesman for the firm said that, by 1pm, staff were back in the building and working and she extended her thanks to neighbouring firms who assisted the company during the fire.

By midday, the roads around the propeller factory were reopened and traffic started to flow again.

A spokesman for the Health and Safety Executive said: "Two of our inspectors have been on site. They will make a decision whether an official investigation needs to be launched.

"If they do, they will write a full report and decide to either prosecute to recommend improvements."