LONDON (USA TODAY) -- LONDON — British authorities on Monday released the names of two of the three men who killed seven and injured dozens over the weekend.

"While formal identification has yet to take place, detectives believe they now know the attackers’ identities. They believe two of the men are Khuram Shazad Butt and Rachid Redouane, both from Barking, east London," police said in a statement.

Butt, 27, was a British citizen who was born in Pakistan, police said. Redouane, 30, had claimed to be Moroccan and Libyan. He also used the name Rachid Elkhdar, with a different date of birth. Inquiries are ongoing to confirm the identity of their accomplice, police said.

NBC News reported Monday that an American bystander was shot in the head by a stray bullet fired by police toward the attackers during the incident on London Bridge and in nearby Borough Market on Saturday night. He is expected to survive.

More people were detained in east London early Monday in connection with the attack. Counterterrorism police raided two addresses in the Newham and Barking areas. “A number of people have been detained and are at present being spoken to,” the Metropolitan Police said in a statement.

Prime Minister Theresa May said the country must do “more, much more” to fight the "evil ideology” of Islamist extremism. She said Britain will review its counterterrorism strategy.

Fabio Lamas, 20, who works at a pub in Borough Market, told NBC he saw the three attackers wearing body armor and brandishing knives before the police arrived.

"I got people to start evacuating inside from our little garden that we have ... and got people to come into the bar and to go into toilets, hide under tables and hide in our cellar where we keep all our stock," he said. "Then I heard shooting and I saw an American guy get shot in the head."

The U.S. Embassy and the Metropolitan Police didn't immediately confirm the report.

The raids came the day after police arrested 12 people in Barking in connection with the rampage. May said Monday that 11 remained in custody and one was released without charge.

May said she thought London Mayor Sadiq Khan was doing "a great job." It followed President Trump deriding and misrepresenting Khan's attempt to calm Londoners after the attack.

“At least 7 dead and 48 wounded in terror attack and Mayor of London says there is "no reason to be alarmed!" Trump tweeted Sunday. Khan had told Londoners there was no “reason to be alarmed” by an increased police presence, and said of the terrorists, “we will never let them win.”

Trump maintained the feud with Khan on Monday, tweeting: "Pathetic excuse by London Mayor Sadiq Khan who had to think fast on his 'no reason to be alarmed' statement. MSM is working hard to sell it!"