Four weapons testers were rescued from a bunker by an armoured vehicle after an explosion at a Ministry of Defence (MoD) site. Although MoD Shoeburyness is a military testing site there are civilians who live within its perimeter.
Around 22lb (10kg) of explosives were involved in the blast at a weapons testing centre at MoD Shoeburyness, near Southend-on-Sea, Essex, according to Essex Fire Service.
The weapons testers were freed by MoD officers in an armoured personnel carrier, but there were no injuries.
Five fire crews attended the incident, which happened at around 11am on Saturday.
A spokesman for QinetiQ, the private defence contractor that runs the Blackgate Road munitions centre, said: "No-one was hurt in the incident at our environmental test centre and we are conducting a full investigation into what happened as is part of our standard safety procedures."
Although Shoeburyness is a military testing site there are civilians who live within its perimeter. There is also a pub and a village shop.
Warning signs alert motorists that ordnance tests are carried out and roads through the site are closed to civilian traffic when tests are in progress.
In August 2002 Terry Jupp, a Government scientist, was killed when a secret bomb-making experiment left him with extensive burns.
An inquest held in 2010 found that the tests – intended to discover more about al-Qaida's bomb-making capabilities – had been poorly planned and organised.
Jupp, 46, who had worked for the Ministry of Defence for more than 20 years, was a member of a joint Anglo-American team conducting the experiment on the island of Foulness, part of the MoD's weapons testing site at Shoeburyness.
The jury at the inquest concluded that planning and risk assessment had not been appropriate.
It found that a small scale test could have been carried out in advance; adequate regard was not paid to personal protective equipment; and communication and organisation at the trials appeared inadequate.