Polling stations were evacuated in south west London after an unexploded Second World War bomb was discovered at a building site.
Police sealed off parts of Kingston on Thursday morning after the explosive was found in Fassett Road at about 9.15am, the Metropolitan Police said.
Shortly before 8.30pm, police said some 1,500 houses had been evacuated as a precaution with cordons expected to remain in place until Friday afternoon.
Commander Mark McEwan said: “Rest centres and assistance are being provided by our partners. Police patrols will continue in order to ensure the area’s safety.
“The operation is likely to continue throughout the night.”
Kingston University’s Penrhyn Road and Knights Park campuses were also evacuated, along with Surbiton High School, where some Year 10 students were sitting exams.
Specialist police officers examined the bomb and called in experts from the Ministry of Defence, the Met said.
Two polling stations were closed, St John the Evangelist church in Grove Lane and St Raphael’s Catholic church in Portsmouth Road.
People taking part in Thursday’s European elections were instead directed to other sites to cast their vote.
Kingston University said all staff and students at evacuated campuses were “advised to go home”.
A statement said some student halls and houses were also evacuated.
The Met said residents told to leave their homes could go to the United Reformed church, in Eden Street, as they waited for cordons to be lifted.
One parent of a pupil at Surbiton High School said exams were postponed and one Latin exam on Thursday morning was abandoned mid-way through when the alarm was raised.
A cordon was expected to remain in place until at least 4pm on Friday, police said, adding that the fire brigade was also involved in the operation.