LONDON, (Reuters) – Five men and one woman suspected of preparing terrorist attacks were arrested during police raids across London on Thursday, the capital’s Metropolitan Police said.

Police said the operation was not linked to the Olympics, which start in London on July 27, but were part of a planned intelligence-led operation.

A 29-year-old man was arrested on a street in west London, while the others, aged between 18 and 30, were detained at residential addresses in east and west London.

A 24-year-old man was tasered during the operation but did not require hospital treatment.

Police said the six were arrested on suspicion of the “commission, preparation or instigation of acts of terrorism” and were taken to a police station in southeast London.

Detectives were searching eight homes in east, west and north London, and one business address in east London.

British security forces are on high alert for any signs of trouble ahead of the Olympics. Seven years ago suicide bombers killed 52 people in a string of coordinated attacks in London.