NBC News' British partner ITV News reported that people in the area said a van struck multiple pedestrians on the bridge.
Ben said: "We saw people running away and then I saw a man in red with a large blade, at a guess 10 inches long, stabbing a man, about three times".
Soon after, there were reported stabbings at nearby Borough Market. My thoughts are with everyone affected, and I'd like to thank the courageous men and women of our emergency services who were first on the scene and will be working throughout the night. Our thoughts are with those who are caught up in these terrible events.
The bridge incident also comes more than two months after a man drove an SUV into a crowd on the sidewalk along Westminster Bridge in London, killing at least four people. He said: "I remember that I was working behind the bar and one man entered into my restaurant and that's it - I remember about the third table, second one, next to the door, a man dropped everything and ran out".
Some 20 people were also said to have been injured.
He said the pub was then closed and armed police told them to leave the area.
One of the men suspected of being involved in the attack was shown in a photograph lying on the ground with canisters strapped to his body after he was shot by the police.
On May 22, a suicide bomber killed 22 people and injured dozens at an Ariana Grande concert in Manchester.
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Edwards said the 2018 deficit is coming because $1.3 billion in temporary taxes passed in 2016 expire on July 1, 2018. Meanwhile, a dispute between House Republicans and Democrats has stalled a construction financing bill.
Police say the incidents occurred on the bridge and at Borough Market a short distance away.
Bartender Alex Martinez said he hid in a garbage bin for a half hour when a man stormed the restaurant where he worked, which was almost full.
There have been no official reports yet regarding casualties, but it is clear from the attending paramedics and active police role in ordering evacuations that the situation is both serious and ongoing.
Roberts said he heard what sounded like gunshots about 10 minutes later.
Italian photographer Gabriele Sciotto, who was watching the Champions League final at the Wheatsheaf pub in Borough Market, said he saw three men being shot just outside the pub.
May said that "following updates from police and security officials, I can confirm that the bad incident in London is being treated as a potential act of terrorism".
Police say armed officers responded to reports of a van hitting pedestrians on the bridge in central London.
"This was a deliberate and cowardly attack on innocent Londoners and visitors to our city enjoying their Saturday night", Khan said. And now tonight, police are not calling this a terrorist attack, but it's an extraordinary evening. He said a panicked store manager told diners to abandon their meals and shelter in the back of the restaurant while police conducted a search of the area. "People running - I've never ran so fast in my life", Joe Dillon, an American grad student at Kings College, told MSNBC.
"My thoughts are with everyone affected, and I'd like to thank the fearless men and women of our emergency services who were first on the scene and will be working throughout the night", Khan added.
This is a breaking news story that will be updated. "There is no justification whatsoever for such barbaric acts", he added.
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