Seven people have died as a result of the attack, with an additional 48 sent to the hospital with injuries, the Metropolitan Police confirmed. Three suspects were shot and killed by police in the minutes following the fatal attack.
Here's a timeline of how Saturday night's events and the aftermath of the attack unfolded.
10:08 p.m. British Summer Time: Police were first called to London Bridge with reports of a white van swerving onto the sidewalk and hitting pedestrians.
BBC reporter Holly Jones, who was on the bridge at the time of the attack, told the BBC that the van was "probably traveling at about 50 miles an hour," adding, "He swerved right round me and then hit about five or six people. He hit about two people in front of me and then three behind."
In the minutes directly after the London Bridge attack, the attackers continued on to nearby Borough Market, where they proceeded to stab customers in some of the area's numerous restaurants and bars. Buzzfeed News reported the stabbings took place inside and directly outside of the Barrowboy & Banker pub, Black & Blue steakhouse, Roast restaurant, Southwark Tavern, El Pastor restaurant and Brindisa restaurant.
One witness at the scene named Gerard told the BBC that he had chased after the attackers as they ran into pubs and restaurants, throwing items at them to get them to stop.
"They were running up shouting, 'This is for Allah.' They stabbed this girl maybe 10 times, 15 times. She was going, 'Help me, help me.'," Gerard recounted to the BBC.
10:14 p.m.: Ambulances arrived on the scene minutes after the initial calls to treat victims, according to the Evening Standard.
10:16 p.m.: The three male suspects were confronted and shot by police within eight minutes of the initial call to authorities, a statement by Metropolitan Police Assistant Commissioner Mark Rowley confirmed.
The suspects were wearing canisters that appeared to be explosive vests, but were later discovered to be fake, the police statement noted.
Buzzfeed News reported the confrontation took place outside the Wheatsheaf pub on Stoney Street, near where the stabbings took place.
10:28 p.m.: Metropolitan Police confirmed on Twitter that they were "dealing with an incident" on London Bridge.
11:43 p.m.: The police confirmed eyewitness reports of the van and Borough Market stabbings. It is also reported that police have responded to an incident in the Vauxhall area of London, which was later revealed to be unrelated.
12:25 a.m. (Sunday, June 4): Metropolitan Police officially declared on Twitter that the London Bridge and Borough Markets attacks are terrorist incidents.
1:24 a.m.: The Sun reporter James Cox reported explosions in the London Bridge area, which were revealed to be controlled explosions by police
The London Bridge area was cordoned off in the aftermath of the attack with restricted access, police confirmed.
10:09 a.m.: Police confirmed that 12 people had been arrested in conjunction with the attack.
The police statement noted that the ongoing investigation was "progressing rapidly."
10:30 a.m.: Following a Cobra meeting with British intelligence officials, Prime Minister Theresa May delivered a speech outside of 10 Downing Street in response to the attack, in which she outlined a four-point plan to help fight against terrorism. She announced the country's general election will go ahead on Thursday as planned.
"We cannot and must not pretend that things can continue as they are," May said during the speech, noting that "terrorism breeds terrorism."