A number of properties in Exeter were damaged following the controlled detonation of a Second World War bomb.
The explosion took place at 18:10 on Saturday evening and it was heard for miles.
The Royal Navy bomb disposal experts and Army personnel from the Royal Logistic Corps (RLC) tried to mitigate the impact of the blast transporting 400 tonnes of sand to the site and erecting walls.
Following the explosion, police said the impact of the blast had been "significant", with debris thrown at least 250m away.
"Unfortunately, structural damage has been caused to some buildings, primarily within the 100m cordon, including blown-out windows and cracks in brickwork," a spokesman for the Devon and Cornwall Police said.
He added that "every effort is being made" to make sure structural assessments are conducted "as soon as possible" to allow residents to return to their homes.
However, on Sunday afternoon Devon and Cornwall Police advised residents to plan for the eventuality that they would not be able to return home that evening.
The force spokesman said it was "impossible to predict" whether safety assessment work would be concluded on Sunday.
"Fencing is being erected this afternoon around those buildings deemed unsafe.
"This is approximately in line with the 100-metre cordon.
"Residents who live within this cordon will not be able to return home this evening," he said.
An update is expected to be issued at about 20:30.
Exeter University is communicating directly with the 1,400 students evacuated from their halls of residence, who are currently staying in alternative accommodation.
The bomb was believed to be a 1,000kg Hermann bomb used by Nazi forces during the conflict.
The device was located on private land to the west of the University of Exeter campus on Friday morning.
Initially, local police forces erected a 100m cordon, but this was then extended to a 400m cordon on Saturday at the request of Royal Navy Explosive Ordnance Disposal (EOD) specialists.
About 2,600 properties in the vicinity of Glenthorne Road, including university accommodations, were evacuated on Friday and Saturday ahead of the controlled detonation.
Residents have been asked not to return to their homes until further notice.
Cover image: Exeter City Council/Twitter.