Police said a man who was driving the auto has been arrested and taken to a.
Nine other people were injured, while the attacker has been taken into police custody.
Metropolitan Police deputy assistant commissioner Neil Basu confirmed that the incident was being treated as a "terrorist attack". A man who was being given first aid at the time died at the scene, but it's not clear if he died as a direct result of the attack.More news: Aussie tourists in Bali duped into eating dog meat
The alleged attacker is now in custody, and a residence in Cardiff, Wales, is being inspected by the police as possibly associated with the incident. A man intent on killing Muslims plowed a rented van into the group of Londoners - killing one and injuring 10 more - before jumping out and taunting them with slurs, according to witnesses.
Monday's incident took place during the Muslim holy month of Ramadan, when worshipers traditionally fast during the daytime and worship at night. A local imam, Mohammed Mahmoud, said he and others shielded the man until police could take him away.
Britain's terrorist alert has been set at "severe", meaning an attack is highly likely.
Many at the mosque, and on social media, criticized the police and the media for what they saw as a too-slow decision to label the mosque attack as terror.More news: Russian diplomat condemns US for downing Syrian fighter jet
Darren Osborne, who police believe was acting alone, was not known to the security services.
She later told reporters Monday, "The people in the Muslim community attending prayers will see their police protecting them in the coming days and nights". "And the reason that so many people have turned up today from all sorts of different faith communities is because we want to stand in solidarity with our Muslim brothers and sisters".
To the north, Manchester was hit by a deadly attack May 22 when a suicide bomber killed 22 people at an Ariana Grande concert. Eight people were killed and dozens were wounded before police fatally shot the three attackers.More news: US Dollar Higher on Fed Outlook
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