London: Seven people were killed in a terror attack in the British capital on Saturday night when a van smashed into pedestrians on London Bridge before three assailants went on a stabbing spree.

The trio were shot dead by the police at the scene.

Here is what we know about the attack, which came 12 days after a suicide bombing in Manchester and five days ahead of a general election.

- What happened? -

Police received reports of a van speeding into pedestrians on London Bridge at 10:08pm (2108 GMT).

These emergency calls were quickly followed by reports of multiple stabbings in the popular Borough Market area on the south side of the bridge.

After the white van crashed into fencing by Southwark Cathedral, knifemen sprinted towards nearby bars packed with revellers enjoying a night out.

Armed police were quickly on the scene and three assailants were shot and killed within eight minutes of the first call to emergency services.

They were wearing what appeared to be explosive vests that were later discovered to be fake.

Police have yet to release any details about the suspects, but Prime Minister Theresa May said they were driven by Islamist ideology.

- How many victims? -

Seven people were killed and 48 others were taken to hospital.

The injured included a police officer who was one of the first responders on the scene. He was stabbed in the face and leg.

A Spanish citizen, one Australian and four French people were also among the wounded.

Several others were treated at the scene for what the ambulance service said were "less serious injuries".

One witness said he saw "five or six" people knocked down on the bridge.

Witnesses in Borough Market reported seeing several people being attacked by the knifemen.

- Was anyone else involved? -

Police on Sunday arrested 12 people in Barking, an ethnically diverse suburb of east London, in connection with the attack.

Sky News reported that the home of one of the assailants was one of the properties raided.

- Where did it take place? -

London Bridge is one of the main arteries leading into the heart of the City business district in the British capital.

Borough Market, at the south end of the bridge, is a world-famous food hall and a trendy nightlife area always packed with revellers on a Saturday night.

The Shard skyscraper -- Britain's tallest building and one of the best-known sights on the London skyline -- is also at the south end of London Bridge.

The scene is right next to London Bridge station, a key railway terminus and a busy interchange on the London Underground network.

The van crashed into fences by Southwark Cathedral and the railway bridge.

- What was the reaction? -

Authorities were already on high alert following other recent attacks. Armed officers and ambulances raced to the scene.

London Bridge station was shut down and police rapidly sealed off the area.

The attacks were declared as "terrorist incidents" at 12:25am Sunday (2325 GMT Saturday).

Pictures showed police leading members of the public away with their hands on their heads.

British and world leaders reacted with a combination of outrage and solidarity.

London Mayor Sadiq Khan described it as "a deliberate and cowardly attack on innocent Londoners and visitors to our city enjoying their Saturday night".

President Donald Trump offered the help of the United States, but also poured scorn on Khan's attempt to reassure the public.

"We must stop being politically correct and get down to the business of security for our people. If we don't get smart it will only get worse," Trump said in a tweet.