UK police were dispatched tonight to "a major police incident" on London Bridge, where it appears a van traveling at a high speed may have deliberately crashed into pedestrians.
It was later reported that several people had been injured in a stabbing and possibly shooting attack in nearby Borough Market and a third incident in Vauxhall area.
According to social media accounts, a white van plowed into pedestrians on or near the bridge, injuring several.
There are also unconfirmed reports of a stabbing attack and of gunshots.
BBC reporter Holly Jones was in the area when the attack occurred.
She told the BBC that a man was driving the van, which was "probably traveling at about 50 miles an hour" when it apparently began mowing down pedestrians.
Jones said the van struck five or six people, and that she witnessed a man later being taken away in handcuffs.
"He swerved right round me and then hit about five or six people," Jones told the channel.
"He hit about two people in front of me and then three behind."
She witnessed the injured being treated by paramedics, she said.
Other estimates say as many as 20 people may have been injured in the incident.
A witness told Reuters she saw people with what seemed to be knife wounds at the scene of the incident, and local residents have reported hearing gunshots.
A witness write on his tweeter : "Horrific scene at London Bridge... bodies strewn over the pavement. B&Q van mounted the pavement. I feel sick"
Another witness write on his tweeter too: “Up to 20 injured. Some sources say van drove into crowd, followed by a stabbing incident. Unconfirmed”.
Armed police are at the scene of the apparent attack, along with helicopters and ambulances.
Police apparently told other pedestrians in the area to flee.
Witnesses describe the scene as "horrific."
The managing editor of The Spectator was apparently on the scene when the incident occurred and is reporting that he saw two casualties, one on the pavement and one in the road, according to British media.
London Bridge is closed in both directions and the London Bridge rail station has also been closed.
British Prime Minister Theresa May has been briefed on the attack and is in contact with officials, Downing Street reports.
US President Donald Trump has also been informed, his press secretary announced.