A BRIGHT white flash lit up the sky as a huge explosion ripped through an Essex industrial unit yesterday.

Roads were closed off, businesses evacuated and emergency rest centres set up following the major blaze in Maldon.

It broke out at Sill-Die in Fullbridge Quay shortly before 1pm but matters escalated when the fire exploded two chemical tanks. Witnesses reported seeing a bright white flash and hearing a huge bang as the phosphorus tanks caught alight.

Forty firefighters were called in to tackle the blaze but were hampered by the presence of magnesium, which has a violent reaction to water.

Police sealed off the area from Station Road to Market Hill and evacuated nearby businesses, including a Tesco superstore.

Maldon District Council set up emergency rest centres at Plantation Hall, Heybridge, and Town Hall, Market Hill, where residents who could not get to their homes were given refreshments.

At 4.40pm spokesman for Essex County Fire and Rescue Service (ECFRS) said: “First one tank exploded and then that made the second tank explode.

“There was a huge bang and the explosion created a bright white flash with pieces of phosphorus flying out everywhere.

“Crews are battling hard at this incident but the chemicals involved are creating problems - parts of the building have already collapsed.”

He confirmed no homes had been evacuated because the fire service’s chemical expert said the toxicity levels were low.

He added it was too early to say how the fire had started.

The flames were out by 5.03pm but crews are expected to be on site throughout the night, turning over and damping down the scene.

The family business, which was founded in 1977, is a manufacturer of foiling and embossing dies. Dies, like molds, are specialist tools used to cut or shape material.

Essex Police and ECFRS said they were not aware of any injuries from the incident.