At least seven people have been killed and 48 injured near London Bridge. The incident occured just 12 days after a suicide bombing in Manchester killed 22 people at an Ariana Grande concert.
At least seven people have been killed and 48 wounded – including police officials and several foreign nationals – in a terrorist attack on London Bridge and the nearby popular Borough Market on Saturday.
Here is what we know so far:
1. The attackers drove a white van at high speed into pedestrians walking on London Bridge at 10:08 pm local (2108 GMT).
After the van crashed into fencing by Southwark Cathedral, three men armed with knives left the vehicle and attacked people in the street, in pubs and restaurants around Borough Market on the south side of the bridge.
Some witnesses said the attackers were "slitting throats".
2. What initially looked like explosive vests worn by the attackers were later established to be fake. Armed police reacted within minutes and three assailants were shot dead at the scene within eight minutes of the first call to the emergency services.
3. Authorities said they were treating it as a "terrorist incident" at 12:25 am Sunday (2325 GMT Saturday). The London Bridge area remains cordoned off.
4. At least 12 arrests have been made. A Reuters' photographer saw four women being escorted into police vehicles in Barking.
"Officers from the Met's Counter Terrorism Command have this morning, Sunday 4 June, arrested 12 people in Barking, east London, in connection with last night's incidents in London Bridge and the Borough Market area. Searches of a number of addresses in Barking are continuing," the statement said.
5. On Sunday, Daesh claimed responsibility for the attack
May said the London Bridge, Westminister and Manchester attacks are not linked by group or logistics. But "perpetrators are inspired to attack [...] by copying one another". She also said the general election will take place as planned.
6. Britain's terror threat levels were elevated to "critical" after Ariana Grande's concert was attacked in Manchester 12 days ago but were downgraded to "severe" five days later.
7. Daesh earlier on Saturday sent out a call on instant messaging service Telegram, urging its followers to launch attacks using trucks, knives and guns against "Crusaders".
The all-star concert to raise funds for Manchester victims went ahead as planned in the north-west city on Sunday.
The "One Love Manchester" concert was headlined by Grande and will also feature Justin Bieber.