At least one person has died and ten were injured when a van plowed into a crowd gathered outside a London mosque after prayers. London mayor Sadiq Khan said police were responding to a “horrific terrorist attack.” Prime Minister Theresa May called it a “potential terrorist attack” and said: “All my thoughts are with those who have been injured, their loved ones and the emergency services on the scene.”

The Metropolitan Police called it a “major incident” and said an investigation was being carried out by the Counter Terrorism Command. Eyewitnesses said there were a total of three “attackers,” one of whom was apprehended while two more fled the scene.

Police said they arrested a 48-year-old man at the scene and that no other suspects had been identified. Two people were treated at the scene and eight were transferred to three London hospitals, according to London Ambulance Service Deputy Director of Operations, Kevin Bate. The incident happened in Finsbury Park in the north of London, in Seven Sisters Road, according to officials.

May will chair an emergency meeting on Monday morning to coordinate the government’s response. The Muslim Council of Britain called the incident a “terror attack” and the “most violent manifestation” of Islamophobia. Eyewitnesses interviewed by ABC News said people were gathered outside the mosque after prayers tending to an old man who was having a heart attack when the van drove into them.

There were men, old men and women, no children. Anywhere from five to 11 people were mowed down, the witnesses said. Khan called it “a deliberate attack on innocent Londoners, many of whom were finishing prayers during the holy month of Ramadan.

“While this appears to be an attack on a particular community, like the terrible attacks in Manchester, Westminster and London Bridge it is also an assault on all our shared values of tolerance, freedom and respect,” Khan said in a statement. A man identified as Jermain Jackman told the BBC the sidewalks were “packed with people walking home” when the incident occurred.
“It was a van that mounted the pavement as men and women were leaving the mosque to go home to their families and friends and their loved ones,” Jackson said. “During the night, ordinary British citizens were set upon while they were going about their lives, completing their night worship,” the Muslim Council said in a statement, adding that “Muslims have endured many incidents of Islamophobia,” over the past weeks and months.

“We urge calm as the investigation establishes the full facts, and in these last days of Ramadan, pray for those affected and for justice,” the statement concluded. One person was in custody and the investigation was ongoing, police said. Britain set its terror at “severe,” meaning an attack is highly likely, after a pair of incidents recently.

Earlier this month, a van rammed pedestrians on London Bridge, setting off vehicle and knife attacks that left eight people dead and many other injured on the bridge and in the nearby Borough Market area. Three Muslim extremists who carried out the attack were killed by police. There was also an attack at an Ariana Grande concert in Manchester, where a bomber set off an explosion that killed more than 20 people.