LONDON (AP) – A bomb scare that prompted the military to begin airlifting workers from a North Sea oil rig Sunday was a false alarm, police said.

Helicopters had begun evacuating workers from the Safe Scandinavia oil platform 170 miles off the coast of Aberdeen in eastern Scotland in response to a security alert from the rig at about 9:30 a.m. (4:30 a.m. EST), officials said.

The operation was called off at about 2 p.m. (9 a.m. EST). Nearly 100 workers of the 539 employees on the rig had been evacuated, police in Scotland said.

A 23-year-old British woman was being taken ashore for questioning, police said. The incident was not terrorism-related, authorities said.

“It is understood the incident was sparked by comments made by a woman on the installation,” Britain’s Royal Air Force said in a statement.

Sky News television said “a hoax” by the employee had led officials to believe there was an explosive device on the rig.

A fleet of about a dozen helicopters, a Nimrod patrol aircraft and an AWACS surveillance aircraft had been commanded to the scene, and a military bomb disposal team had been on standby, officials said.

Workers were being return to the rig, the Ministry of Defense said.