A van crashed into a crowd at London Bridge and a series of stabbing nearby were confirmed by Metropolitan Police.
One report is that someone was shot by police, lying on the ground "with what appears to be canisters attached to his body. This has not been confirmed.
The attack began around 10:00 p.m. local time. Witnesses said that it did not look accidental. Gunfire erupted at the bridge, though it may have come from the police.
A woman witness at nearby Borough Market was at a restaurant and told Britain's Press Association that three men entered, then "stabbed someone in the face and someone in the stomach. One of them had a big knife, then he came in and walked around the restaurant, I guess they just kind of stabbed anyone that they saw and knocked things on the ground and then we just hid."
Another Borough Market witness identified only as Ben, told the BBC, "We saw people running away and then I saw a man in red with a large blade, at a guess ten inches long, stabbing a man, about three times." He then added, "It looked like the man had been trying to intervene, but there wasn't much he could do. He was being stabbed quite coldly and he slumped to the ground."
Thus far, it isn't known the number of injuries.
British media is calling the attack cowardly, but it was brutal and Islamic, not cowardly.
Prime Minister Theresa May and President Trump have been briefed and updated.
Another stabbing at Vauxhall was determined to be unrelated to this attack.
Theresa May will lead a meeting of the emergency response committee Sunday.
President Trump tweeted: "Whatever the United States can do to help out in London and the U.K., we will be there- WE ARE WITH YOU. GOD BLESS!"
The U.S. State Department told the media: "We stand ready to provide all possible consular assistance should we become aware of any affected U.S. citizens. We strongly encourage U.S. citizens in the United Kingdom to directly contact concerned family members in the United States to advise them of your safety."