In pictures: London Bridge attackPAPolice responded to reports of a van hitting several people on London Bridge.Getty ImagesThe surrounding area was quickly closed to the public.PAArmed officers were on the scene within minutes.PAEyewitness reports said the van mounted the pavement of the bridge.H. AttaiA white van is thought to have mounted the pavement, attackers are then thought to have descended on the busy Borough Market area.ReutersPolice locked down the Borough Market - known for its restaurants and bars - where several of the victims are thought to have been stabbed.Gabriele SciottoOne social media user published a picture of a man on the ground with what appeared to be canisters strapped to his body. These explosive vests were later confirmed to be hoaxes.PAOfficers went into bars and told people to get on the floor while they secured the area.Dominic LipinskiPolice said seven people had been killed and three suspects shot dead.PAPolice told people to be "calm, alert and vigilant".PALondon Ambulance Service declared a major incident.AFP/GettySome injured people were treated at the scene - 48 people, some critical, are being treated in five hospitals.EPALondon Bridge station was closed shortly after the attack.Reuters Facebook activated a safety check so people could let friends and family know they were safe.AFP/GettyAn emergency response helicopter landed on London Bridge.Getty ImagesPrime Minister Theresa May said it was being treated as a "potential act of terrorism".ReutersThe area remains closed as police and forensics experts conduct their investigations.Latest updates: London attackSeven killed in London terror attack