Three police officers were injured and 40 people arrested during a protest in Westminster on Tuesday night, Scotland Yard said. One officer was left with a serious facial injury after she was hit by a bottle thrown from the crowd, while two officers had minor injuries. Metropolitan police said the suspect who threw the bottle had not been identified but police were investigating. A protest organised by a coalition of groups, including the Palestine Solidarity Group, began about 6pm and was required to end at 8pm, police said. Most of the crowd, which was between 8,000 and 10,000 people, left Whitehall without incident. A group of about 500 people remained and police began making a number of arrests for failing to comply. Police said some of the crowd resisted arrest, which required officers to use force to remove those who had been arrested. The protest then broke away, with the crowd marching to Bridge Street, outside Westminster station, where officers put up cordons to detain them. Police went into the crowd shortly before 10pm to arrest those suspected of leading the breakaway protest, the Met said. There were 40 people arrested for offences including breaking the Public Order Act, obstruction of a highway and assaults of emergency workers. Around 2am on Wednesday, police said all protesters had left the area and Bridge Street had been reopened.