An unexploded second world war bomb discovered in a school playground in Bath has been made safe. Police said the 500lb bomb was deactivated by experts from the explosive ordnance disposal unit on Friday night.

The exclusion zone in the city will remain in place while the bomb is removed from the site to be disposed of. Ch Supt Ian Smith, the area Commander for Bath, thanked residents and local businesses who had been affected by the incident.

“Thank you for your patience, cooperation and support throughout the last 24 hours,” he said. “We have worked as quickly and diligently as possible to limit the disruption caused but, as you can expect with an incident of this nature, public safety has to be our primary concern.

“As soon as the cordon is removed and all roads are clear, we will update all the local residents so they can return home.”

The 300-metre exclusion zone was set up after the bomb was discovered at Royal high school on Lansdown Road, Bath, at 4.40pm on Thursday. Contractors unearthed the second world war bomb from beneath the surface of the school’s playground, which had been in use until two years ago.

Residents from 1,100 properties nearby were advised to evacuate immediately. Three primary schools were closed, along with a doctor’s surgery, and drivers were asked to consider if it was “absolutely necessary” for them to travel into the city.