31 minutes ago
A van has struck pedestrians on London Bridge in central London and the occupants have attacked people around nearby Borough Market. Police have declared a "terrorist incident".
Here's what we know so far.
Police and ambulance could be seen on the south side of London Bridge
The first reports were centred on London Bridge
Armed police and ambulances were called to reports of a white van hitting several people on London Bridge at 22:08 BST on Saturday.
The area and nearby railway stations were closed. Witness reports said the van mounted the pavement and swerved into a number of people.
The white van, in the centre of this photo, is believed to have been used in the attack on London BridgeImage copyrightH. ATTAI
The white van, in the centre of this photo, is believed to have been used in the attack on London Bridge
BBC reporter Holly Jones, who was on the bridge, said: "A white van driver came speeding - probably about 50mph - veered off the road into the crowds of people who were walking along the pavement.
"He swerved right round me and then hit about five or six people."
The vehicle continued to drive to nearby Borough Market, where the suspects stabbed several people in an area crowded with people having an evening out.
The Metropolitan Police confirmed six people had died and at least 30 required hospital treatment. In addition, three suspected attackers were shot dead.
British Transport Police said one of its officers was seriously injured responding to the attack.
A third police unit was sent to the Vauxhall area. Officers later said this was a stabbing and not connected to the operation at London Bridge and Borough Market.
Map of London Bridge and Borough Market
The Metropolitan Police said six people died in the attack.
London Ambulance Service said it had taken at least 30 people to five different London hospitals.
The "seriously injured" British Transport Police officer suffered head, face and leg wounds.
Meanwhile, people described as "walking wounded" were moved to the Andaz Hotel at Liverpool Street where there were paramedics and more armed police.
Counter-terrorism specialist firearm officers were in attendanceImage copyrightGETTY IMAGES
Shots were later fired in the area around Borough market to the south of the bridge
Police boats also searched the River Thames for anyone who may have fallen from the bridge.
The Metropolitan Police has opened its Casualty Bureau for people concerned about friends or relatives. No victims have yet been named.
Man on ground at Borough MarketImage copyrightGABRIELE SCIOTTO
Gabriele Sciotto's photo appears to show a man with canisters around his waist
Three men, believed to be the attackers, have been shot by police.
Police said the men were shot within eight minutes of officers receiving the first reports of the attack.
Witnesses had described seeing between two and four men getting out of the van after it crashed south of London Bridge.
Police confirmed shots were fired at Borough Market and a photographer took a picture showing two people lying on the ground outside the Wheatsheaf pub.
One of the people on the ground appears to have canisters strapped around his waist, and police said the men were wearing hoax explosive vests.
The person who took the photo said he saw three people shot by police.
What is currently happening?
The investigation is being led by the Counter Terrorism Command.
London Bridge is completely closed and will remain so, British Transport Police said.
Police believe they may have caught all the attackers but armed officers continue to sweep the area.
London Bridge and Borough stations have been closed and trains are passing straight through.
Network Rail also said Waterloo East, Charing Cross and Cannon Street stations were closed and there were delays at Blackfriars.
The River Thames has been reopened to boats.
Nearby Guy's Hospital has been placed in lockdown as a precaution to keep staff and patients safe, as have St Thomas' and the Evelina Children's Hospital a mile away.
Media caption"Get down" - police enter bar at London Bridge
Police have been clearing streets, bars and restaurants around Borough Market, a very busy area of the capital especially on Saturday nights.
Prime Minister Theresa May and Mayor of London Sadiq Khan both said they are being kept "regularly updated" on events.
Mrs May said: "Our thoughts are with those who are caught up in these dreadful events."
The prime minister will chair a meeting of the government's Cobra emergency committee on Sunday, which Mr Khan will attend.
Mr Khan described the events as a "deliberate and cowardly attack on innocent Londoners and visitors to our city enjoying their Saturday night".
Labour leader Jeremy Corbyn called the attack "brutal and shocking".
Lib Dem leader Tim Farron said it was a "horrific incident" and Scotland's First Minister Nicola Sturgeon called it "dreadful news".
The US State Department said it "condemns the cowardly attacks targeting innocent civilians in London".
French President Emmanuel Macron said his country "is more than ever at the side of the United Kingdom".
Residents and businesses in the area have been offering shelter to people. The hashtag #SofaForLondon has been used to share offers.