Three men, believed to be plotting a terror attack in the United Kingdom, were arrested by counter-terrorism detectives on Thursday, reported The Guardian. The police said they were arrested from East London. The arrests were unrelated to the investigation into the London Bridge attack, said Scotland Yard.

Two men, aged 34 and 37, were arrested from Newham, while a third was arrested from Waltham Forest. The three were detained on suspicion of preparation or instigation of terrorism offences and taken to south London police station for questioning. The operation was conducted overnight and searches were still on in their respective homes, added the report.

“All three were arrested on suspicion of the commission, preparation or instigation of terrorism offences under section 41 of the Terrorism Act 2000,” the Metropolitan police said. “They have been taken into custody at a south London police station and are detained under the Terrorism Act.”

Earlier on Thursday, polling stations opened across the United Kingdom for nearly 46.9 million people to cast their votes in the country’s general election. Voters from across England, Wales, Northern Ireland and Scotland will pick 650 MPs from over 3,300 candidates.

Thursday’s arrests were a joint operation by Scotland Yard’s counter-terrorism command and the domestic security service MI5, who are on high alert after the London attack on June 3, where eight people had died. A van had driven into people near the London Bridge in central London last Saturday night. Incidents of stabbing were also reported at the nearby Borough Market.