Armed police respond to serious incidents in three locations in London – London Bridge, Vauxhall and Borough Market.
The first report was of a van ploughing into pedestrians on London Bridge.
A second incident is ongoing in Borough Market where there are reports of multiple stabbings.
Police are also responding to an incident at Vauxhall, Scotland Yard said.
The Metropolitan police have said: “ The incident at Vauxhall is a stabbing and is not connected to the incidents at London Bridge and Borough Market.”
— Metropolitan Police (@metpoliceuk) June 3, 2017
Prime Minister Theresa May has said the “terrible incident” in London is being treated as a “potential act of terrorism”.
London terror attack: London Bridge, Borough Market and Vauxhall latest – at least two dead amid van attack, stabbings and gunfire, the Telegraph said. According to the newspaper: A series of co-ordinated terror attacks have hit London in three different areas, with reports of dozens of casualties from stabbings and pedestrians mown down by a vehicle.
A security guard who oversees a number of pubs in the area has told the BBC he saw four people stabbed by three attackers.
The man, who was deeply shocked and asked not to be named, said he was at the Market Porter pub when a colleague at another bar said there was a stabbing at the Borough Bistro pub nearby.
He said he went towards this pub and saw that “everybody started running” and there was screaming.
The eyewitness added that he saw three attackers, one of whom had a long knife and stabbing people, including a girl in her early 20s.
There are reports of a number of casualties after an incident that possibly involved a vehicle and a knife in the London Bridge area, quoting the British Transport Police, the BBC said.
London Bridge has been closed after an incident on Saturday night, after witnesses said a van had hit pedestrians, the Guardian reported.
The Metropolitan police are urging people in the areas of the incident in Vauxhall, London Bridge and Borough Market to get to safer areas away from the scenes.
Downing Street said: “The prime minister is in contact with officials and is being regularly updated on the incident at London Bridge.”
Jeremy Corbyn, the Labour leader, said on Twitter: “Brutal and shocking incidents reported in London. My thoughts are with the victims and their families. Thank you to the emergency services.”