The Metropolitan Police in London have responded to a situation that they are "dealing with an incident" on the London Bridge.
Witnesses at the scene told the BBC that a white van ran into pedestrians on the bridge.
Metropolitan Police have tweeted that they have officers on scene, and are asking people to avoid the area.
Photos from the scene show heavy police presence on the bridge.
This is a developing story, and will be updated as more information comes in.
Updated at 6:17 p.m. 6/3:
Eye witness accounts from the BBC report that at least five or six people were hit by a white van on the London Bridge, and that several people were being treated by paramedics.
The Metropolitan Police have also confirmed that they have responded to another incident at Borough Markets, where they have sent armed police.
Updated at 6:40 p.m. 6/3:
The BBC has reported that the police are searching for three suspects in relation to the Borough Market incident.
Press Secretary Sean Spicer has tweeted that the President has been briefed on the incident and will continue to provide updates.
Updated at 6:50 p.m. 6/3:
Metropolitan Police are responding to a third reported incident at Vauxhall, they confirmed via Twitter, which is in a separate part of the city. Metropolitan Police have also posted instructions in the case that someone is caught in the situation, which can be seen immediately below.
Metropolitan Police have also tweeted and confirmed that shots had been fired in Borough Market.
Updated at 7:28 p.m. 6/3:
According to multiple reports, police have confirmed that there have been multiple fatalities, but have not confirmed a specific number yet.
Updated at 7:50 p.m. 6/3:
Incidents at London Bridge and Borough Market have been confirmed as terrorist attacks by the Metropolitan Police. The incident at Vauxhall was an unrelated incident, according to the police department.
Updated at 8:50 p.m. 6/3:
The Mayor of London, Sadiq Khan, has released a statement condemning the "horrific terrorist attacks at London Bridge and Borough Market."
"London Bridge Station is closed and we are asking people to avoid the area," said the Mayor Khan in his statement. "The situation is still unfolding and I would ask all Londoners and visitors to our city to remain calm and vigilant. Please report anything suspicious to the police, but only call 999 in an emergency."
Updated at 9:45 p.m. 6/3
The London Ambulance Service has confirmed that they have taken at least 20 patients to the hospital following the attacks, and that other patients with less serious injuries were treated at the scene.
Updated at 11:09 p.m. 6/3
Assistant Commissioner Mark Rowley has released a statement, confirming that six people were killed in relation to the London Bridge and Borough Market attacks, as well as the three attackers who were shot and killed by police.
“We are reviewing and planning to strengthen our policing stance across London over the forthcoming days," said the release from Rowley. "There will be additional police and officers deployed across the Capital."
He urged the public to report any information regarding the attacks to report to the Counter Terrorism Command, which is leading the investigation into the incident. He also reaffirmed the call by authorities for the public to stay vigilant and said that thoughts were with the victims and first responders to the incident.