Three men were hospitalised after an explosion at a Stevenage industrial unit early this morning.

The men, aged 48, 50 and 52, were taken to Lister Hospital by ambulance suffering from smoke inhalation after an industrial oven used in the making of electrical circuits exploded, blowing the door off, catching fire and filling the building with smoke.

The emergency services were alerted to the fire at Stevenage Circuits in Caxton Way at 1.18am. Two Stevenage fire crews dealt with the blaze, while paramedics treated the men who had evacuated the building.

A chemical specialist was called by the fire service to advise the crews and the fire was declared out at 2.40am.

No other premises were threatened and the cause was non-suspicious Hertfordshire Constabulary said.

After being checked over, the three men involved returned to work one hour after the incident.

Tim Gee, operations manager at the company, which supplies computer circuits to the military, aerospace, communications and medical industries, said: “We had a small fire in an oven. Only the oven was damaged but there was some fumes released from the oven so just as a precaution we took three people to hospital.

“It’s a very minor incident as far as we’re concerned but being a responsible company we have to edge on the side of caution and that involved calling the fire brigade and a trip to the hospital ward.”

An investigation into the matter has not yet been launched by the Health and Safety Executive.

A spokesman said: “The Health and Safety Executive is aware of the incident and is making enquiries.”

The incident follows a chemical spill in Royston last August at a disused industrial unit owned by Tru-Lon Printed Circuits - a member of the Stevenage Circuits Group.