ATHENS — In Greece’s biggest peacetime evacuation ever, about 72,000 people left their homes in the city of Thessaloniki on Sunday as experts defused and removed a World War II bomb from below a gas station.

Hundreds of police officers in Thessaloniki, the country’s second-largest city, began knocking on doors early in the morning to remind residents within a radius of two kilometers, about 1.2 miles, to leave their homes.

Though residents had been given several days’ warning, with leaflets posted around the city and an online campaign by the local authorities, some were reluctant to leave and had to be convinced by the police that their properties would remain intact. “The security measures might be excessive, but it’s better to be excessive and be safe,” Greece’s public order minister, Nikos Toskas, warned in a televised message.