Boats nearby rescued the officers and they were treated at the scene before going to hospital.
Five police officers who were injured in a boat crash in central London were responding to a report of a “person in the water”, the Metropolitan Police has said.
A boat from the force’s marine policing unit carrying armed officers crashed into Westminster Bridge on the River Thames at around 3.40pm on Friday.
Officers were responding to a report of a person in the water near Battersea, south-west London, when their boat hit the bridge, throwing three of them into the water, the Met said.
Boats nearby rescued the officers and they were treated at the scene before going to hospital, where four remain with serious but non-life-threatening injuries.
One officer has been discharged from hospital.
No members of the public were injured in the incident, the force added.
Met Police Commander Nick John said: “Our thoughts are with all those involved, in particular our officers who were injured and those who responded in challenging circumstances.
“The four officers who remain in hospital have serious but non-life-threatening injuries. We will give them all every support as they recover.
“I must also offer our thanks to those river users who came to the aid of the officers, as well as other police and emergency service colleagues who immediately made their way to the scene to assist.
“The quick-thinking and professionalism of all those involved undoubtedly prevented any further injuries.”
A couple from the United States, who were nearby when the crash happened, said they heard “an explosion” when the boat struck the bridge, adding it was travelling at “high speed”, seemingly in pursuit of something further up the river.
Jim Bagley, who was visiting the capital from Gloucester, Massachusetts, with his wife, told the Press Association: “We were standing in line to get onto the city cruise hop on, hop off tours, and we saw two police boats coming up the river.
“One was an orange boat that went under the bridge and left a great big wave, and then there was a black boat that came up behind it, the police boat.
“It looks to me that he got stuck in the wake of the other boat that had just passed through the bridge and slammed into the wall on the opposite side.
“We didn’t see it happen, but we heard the explosion… the next thing we saw was three people in the water, coming down the river.”
The couple then saw other boats on the river attempt to save those stranded in the water, throwing a cargo net and a life ring into the water.
Mr Bagley said: “There was another boat that came up from the river that had an open transom, and they were able to back into the people in the water and drag them onto the back of the boat.”
He added: “We were wondering why they were under way at high speed to begin with. We don’t know why they were being called upriver.”
His wife, Katherine, said: “They were both in pursuit of something farther down the river, but they never… the second boat never got to it because it crashed into the bridge with a big bang.”
A 19-year-old student, who is on holiday in London from Germany, told PA the collision sounded like a “car crash”.
Enno, who did not want to give his last name, said he was walking over the nearby Hungerford Bridge when he heard a “crashing sound”.
He added: “A black boat had crashed into the side of the bridge by the pier. I think around five police officers were in the water at the same time.
“They looked hurt, but not that much.”
He added: “It sounded like a car crash from around 10 metres away. I had seen the black boat pass under the bridge and once I heard the sound, I saw that it had crashed.”
