A man initially thought to have been stabbed on Westminster Bridge following a fight actually suffered a cardiac arrest, police said.
The Metropolitan Police were called to the bridge at around 10.45am on Sunday after a fight reportedly broke out on the central London Bridge.
The force said initial reports suggested the man had been stabbed, but further inquiries confirmed this was not the case.
He was taken to hospital in a critical condition, according to officers. Three people were arrested on suspicion of attempted murder and one person has been arrested on suspicion of affray.
Two of them have been taken to hospital for minor facial injuries. A road closure is in place on the bridge and police have said inquiries into the incident are ongoing.
A user of X, formerly Twitter, posted online: “Westminster Bridge closed in both directions. Hundreds of Police at the scene with the Bridge cordoned off. What’s going on?”
Anyone with information is asked to call police on 101 quoting CAD 2468/24NOV. Alternatively, people can contact the independent charity Crimestoppers on 0800 555 111 or visit crimestoppers-uk.org.
A London Ambulance Service spokesperson said: We were called today (Sunday) at 10.46am to reports of an incident on Westminster Bridge, SW1.
“We sent a number of resources including ambulance crews, an advanced paramedic, an incident response officer and London’s air ambulance. We treated a man at the scene before taking him to hospital.”