Structural damage has been caused to a number of properties in Exeter following the detonation of a World War II-era bomb, police in England said.

The device, believed to be a 1,000kg "Hermann" bomb used by the Nazis, was discovered on a building site on private land to the west of the University of Exeter campus on Friday morning.

Initially, a 100-metre cordon was erected, but this was extended to 400m yesterday at the request of the Royal Navy bomb disposal team.

Residents at around 2,600 properties in the vicinity of Glenthorne Road, including 1,400 university students, were evacuated.

The controlled detonation of the device took place at 6.10pm yesterday, with the explosion heard for miles.

To mitigate the impact of the blast, around 400 tonnes of sand was transported to the site and walls were erected by the Royal Navy bomb disposal experts and Army personnel from the Royal Logistics Corps.

A spokesman for Devon and Cornwall Police said: "However, unfortunately structural damage has been caused to some buildings, primarily within the 100-metre cordon, including blown-out windows and cracks in brickwork.

"Every effort is being made this morning to ensure structural assessments are conducted as soon as possible so that residents can return home later today."

Police are working with agencies, including Devon County Council, Exeter City Council and utility companies, in the hope that residents will be able to return home today.

The force spokesman added that residents should not return until further notice.

Police said the impact of the blast had been "significant", with debris thrown at least 250 metres away and a crater around the size of a double decker bus.

There are no concerns regarding the impact of the explosion, which caused a large plume of sand, on public health grounds, the force confirmed.

It had previously been expected that residents, the majority of whom are staying with friends and family, would be able to return home yesterday.

Devon County Council confirmed that visiting friends and family was allowed in such circumstances, despite Covid-19 restrictions.

Exeter University asked students not to return to their residences to allow safety assessments to be conducted.