The man suspected of ramming a van into a crowd exiting Ramadan prayers at a London mosque early Monday was spotted on video blowing a kiss at bystanders as he was hauled off to a hospital for a mental health evaluation.
At least one person was killed and 10 others were injured in the attack, which authorities were treating as a terrorist attack.
A 48-year-old man was arrested in the collision with pedestrians outside the Muslim Welfare House, Metropolitan police said.
The incident occurred outside the Finsbury Park Mosque shortly after midnight after Ramadan prayers. Police said all of the injured were members of the Muslim community. Muslim leaders called the attack a hate crime and asked the public to stay calm.
Police said eight of the injured were taken to three hospitals and two suffered minor injuries and were treated at the scene.
A leader of the Muslim Council of Britain called for extra security at mosques in light of the apparent attack. The group's general secretary, Harun Khan, described the incident as a hate crime against Muslims.
"During the night, ordinary British citizens were set upon while they were going about their lives, completing their night worship," he said. "It appears from eyewitness accounts that the perpetrator was motivated by Islamophobia."
London Mayor Sadiq Khan, the first Muslim to serve in that position, said extra police would be deployed. He called the incident a "horrific terrorist attack."
The chairman of the Finsbury Park Mosque said the van crash that hit worshippers was a "cowardly attack" and urged Muslims going to mosques to be vigilant.
Mohammed Kozbar said the Muslim community is "in shock." He complained that the "mainstream media" was unwilling to call the attack a terrorist incident for many hours.