A man who died after an electricity sub-station explosion is believed to be from the Colchester area.

Black toxic smoke billowed into the blue sky across Chelmsford after the incident at an electricity sub-station close to the Rivermead campus of the Anglia Ruskin University, in Bishop's Hall Road.

The explosion happened at about 12.15pm yesterday and was followed by a huge fire.

Emergency services were quickly on the scene.

About 8,000 students were quickly evacuated from the campus buildings by university staff.

A 200-metre exclusion zone was set up around the site.

The man who died has not been named, but he worked for power company EDF Energy.

It is believed he came from the Colchester area but no details have been released.

An EDF spokesman said: "The emergency services believe that, sadly, a member of our staff has died at the scene.

"Our thoughts are with the family of the person involved.

"EDF Energy Networks has initiated its own investigation and we are co-operating fully with the Health and Safety Executive and Essex Police investigations."

Power to thousands of homes, offices and shops, as well as traffic lights around Chelmsford town centre, were cut. Most of the supplies were restored yesterday. Everything was reconnected by 5am today.

EDF's spokeman added: "We still await permission from the Health and Safety Executive and Essex Police to access all areas of the substation and, as yet, have not been able to properly assess the damage."

Neil Fenwick, assistant divisional officer for Essex Fire and Rescue Service, described it as "a major incident".

He said an explosion at the sub-station had caused the fire, which "developed rapidly".

About 40 to 50 firefighters were called to the scene, with fire engines arriving from all over Essex.

Broomfield Hospital, Chelmsford Crown Court and Essex Police headquarters were among the many buildings whose power was cut.