Image copyright @ReqsFireDog Image caption Emergency services, including two air ambulances, were called to Plumpton Road on Saturday afternoon

Two men have been killed and a third injured in an explosion at an industrial unit in Hertfordshire.

The blast happened at about at 16:40 BST on Saturday at Plumpton Road in Hoddesdon.

A man in his 30s and another in his 40s, both from Wood Green in London, died from their injuries at Broomfield Hospital in Chelmsford.

Hertfordshire Police said a man had been arrested on suspicion of manslaughter by gross negligence.

Image copyright South Beds News Agency Image caption Investigators were trying to establish the cause of the explosion at the unoccupied industrial premises on Sunday

Image copyright South Beds News Agency Image caption A third victim was treated and discharged from hospital at Harlow in Essex

A third victim, who is in his 20s, was taken to the Princess Alexandra Hospital in Harlow but has since been discharged.

Police said the arrested man is a 40-year-old from Hoddesdon. He was also being questioned on suspicion of health and safety offences.

The fire service tweeted to say it had received "numerous calls to a building fire".

The scene remained cordoned-off on Sunday while investigations took place.

Police said the unit was currently unoccupied, but it was believed the men may have been carrying out some form of work there.