At least seven people have been killed in the UK capital after a van ploughed into pedestrians on London Bridge and attackers went on stabbing spree in the nearby Borough Market area before being shot dead by police. 

Another 48 people were also wounded in the attack late on Saturday, which occurred in a busy area with many restaurants and pubs.

Mark Rowley, Britain's top anti-terrorism officer, said armed police rushed to the scene "and confronted the three male suspects who were shot and killed on Borough Market.

"Sadly, six people have died in addition to the three attackers shot by police," he added.

The suspects were wearing what appeared to be suicide vests, but police said they were later established to be fake.

There was no immediate claim of responsibility.

Al Jazeera's Yao Chin, reporting from London, said witnesses saw "a white van ram into pedestrians hitting several people before coming to a halt".

"Another witness said three men got out with long blades and randomly started stabbing people along Borough High Street. Other witnesses have also mentioned seeing knife victims," he said.

Police said in a statement that officers "responded to reports of a vehicle in collision with pedestrians on London Bridge" and then "to reports of stabbings in Borough Market".

Police ruled a third incident - a stabbing in London's Vauxhall area initially thought to be linked to the other two scenes - to be unrelated.

One of the men suspected of being involved in the attack was shown in a photograph lying on the ground with canisters strapped to his body after he was shot by the police.

The possible attacker was shown on the ground outside the Wheatsheaf pub in Borough Market near London Bridge.

Another man was seen lying on the ground a short distance away in the photograph.

"There is a huge police presence, emergency services are all over the place," said Al Jazeera's Oliver Varney from the scene.

London Mayor Sadiq Khan described the incidents as a "deliberate and cowardly attack on innocent Londoners".

Al Jazeera's Charlotte Bellis was near the bridge at the time of the attack.

"Paramedics had [those injured] on their sides, it was a bloody scene," she said.

"Some were injured about 50 meters behind the van, some were injured about 10 metres from where the van stopped."

Prime Minister Theresa May's office said she was "in contact with officials and is being regularly updated on the incident at London Bridge".

May's office said she would chair a meeting of the government's COBRA emergency committee on Sunday.

Max Abrahms, an assistant political science professor at Northeastern University, told Al Jazeera it was "clear we are dealing with a coordinated attack in two close-by locations, in very public areas".

London's transport authority said London Bridge rail station had been closed at the request of the police.

Three major London hospitals were placed on lockdown shortly after the attack.

"Due to the ongoing incident in central London, Guy's, St Thomas' & Evelina London are on lockdown to keep patients, relatives and staff safe," the authority that runs the hospitals said on Twitter.

'Shocking' tragedy

The attack came days ahead of a June 8 general election, almost two weeks after 22 people were killed in a bombing at a concert in Manchester.

After that attack, Britain's official threat level was raised to "critical", meaning an attack may be imminent. Several days later it was lowered to "severe", meaning an attack is highly likely.

In March, an attacker ran down people with a vehicle on Westminster Bridge, killing four before stabbing a policeman to death outside Parliament.

World leaders quickly took to social media to offer their support to the people of London.

"Faced with this news tragedy France is now more than ever supporting the UK. My thoughts are with the victims and their loved ones," tweeted French President Emmanuel Macron.

Australia's foreign minister described the incidents as a "shocking".

PHOTO CAPTION

Idle buses are seen from the west side of London Bridge after an incident in the area in London, Britain June 4, 2017. REUTERS

Al-Jazeera