Police and ambulance could be seen on the south side of London Bridge. Image: BBC

Update [03:35 AM PST]: Several more witnesses have reported hearing gunshots.

"We were in an Uber going towards London Bridge and suddenly we saw people running. The Uber stopped, we asked people what was going on ? people said there was shooting," said 40-year-old Yoann Belmere, a French banker living in London, said.

"Now the area is completely closed with police cars going one way and ambulances going the other," he told Reuters.

Update [03:34 AM PST]: Prime Minister Theresa May is said to be in contact with the officials after the incident in London, BBC reported quoting Downing Street.

Update [03:33 AM PST]: US President Donald Trump's national security team has briefed him on the situation at London Bridge, White House spokesperson Sean Spicer said on Twitter. 

Spicer added the team "will continue to provide updates".

Update [03:30 AM PST]: British transport police stated there were casualties after the incident that possibly involved a van and knife injuries, BBC reported.

Update [03:22 AM PST]: Another incident was reported at the Borough Market, to which the British armed police said they were responding alongside the one earlier at London Bridge.

Update [03:18 AM PST]: Three people were allegedly injured and seen lying on the floor, a BBC employee citing multiple witnesses told BBC.

Update [03:15 AM PST]: A witness told the BBC she saw a speeding white van veering into pedestrians.

Update [03:10 AM PST]: A local resident says gunshots were heard near the London Bridge, Sky News reported.

Update [03:08 AM PST]: The London ambulance service also mentioned it is responding to the incident.

The statement provided by a witness earlier has not been immediately verified.

Update [03:04 AM PST]: Multiple resources are now attending the incident at London Bridge, British police mentioned, urging people to avoid the area.

A witness told Reuters she saw people at least three people with what appeared to be throats cut on London Bridge, adding they may be knife wounds.

"Police are dealing with a major incident and all routes are being diverted," the transport agency said on Twitter, as the London Ambulance Service informed that "multiple resources" were being sent to the scene. 

Initial reporting [02:58 AM, Pakistan time]: LONDON: At the request of British police, the London Bridge rail station has been closed on late Saturday night after they reported an incident, local transport authorities said.

The British police have reportedly stated they are dealing with the incident at London Bridge but did not provide any further details.

Reports surfaced that a car mowed down pedestrians on London Bridge, according to Sun Newspaper.

On the other hand, BBC reported citing a witness that a white van veered off the road and hit at least five to six people. On the other hand, 10 police cars were seen speeding towards the London Bridge, a Reuters reporter present at the site stated.

A suicide bomber on May 22 killed 22 people at a pop concert by US singer Ariana Grande in Manchester in northern England.

The Manchester bombing was the deadliest attack in Britain since July 2005, when four British Muslim suicide bombers killed 52 people in coordinated attacks on London's transport network.

?This is a developing story and will be updated as more information is received.