A van ploughed into people, leaving evening prayers at Finsbury Park Mosque. At least one person was killed and eight more were injured as a result of the accident, BBC reported.
Prime Minister Theresa May said police were treating the incident "as a potential terrorist attack". She said she will chair an emergency meeting later this morning.
The Muslim Council of Britain has called for extra security around mosques.
The council's secretary general, Harun Khan, said he expected authorities to step up security "as a matter of urgency", adding many would feel "terrorised" following the incident outside the Muslim Welfare House in Seven Sisters Road.
It was noted that the driver of the van - a man aged 48 - was found detained by members of public at the scene and then arrested by police in connection with the incident.