A policeman has been shot and wounded during an armed operation in east London.
Officers from the Metropolitan Police's Specialist Firearms Command (SCO19) and Trident Area Crime Command were taking part in the operation in Hackney when the shooting happened at around 12.45pm, Scotland Yard said.
The officer was taken to an east London hospital. His next of kin have been informed.
A man was arrested at the scene, police said.
There were no reports of anyone else injured.
A pharmacist who works locally and asked not to be named said he heard a muffled shot and then saw police officers, several armed with guns, immediately arrive on the scene.
He said: "I heard a shot, I looked up and there was a commotion outside the shop. There were a lot of sirens and police cars and a lot of policemen running around all over the place.
"The shot was a muffled sound, it could have been a misfiring of a car engine – but it was quickly obvious what it was. I instantly saw around seven to eight police cars.
"They were an armed response unit, there were officers who had big guns on them. There must have been some sort of operation going on."
He said there is a police safer neighbourhood team office very near where the shooting happened.
He added: "They have put the area on lockdown, cordoning it off with police tape, and I can hear helicopters in the sky.
"There are a lot of police officers still around, they have spoken to me and all the shops around here asking if we witnessed anything.
"I have never experienced anything like it before. It is a bit shocking. There was obviously a police operation going on.
"Everybody hopes the police officer will be OK."
Nilesh Kalawadia, who owns Friends newsagents nearby, heard a bang but didn't realise it was a gunshot.
Mr Kalawadia said: "I thought it was fireworks, I just heard the bang, and saw lots of disruption outside."
"There were lots of police standing outside - 50 or 60. I asked what was going on but a policeman told me it was too early to tell."
Mr Kalawadia added: "I've had to cancel my delivery, it is all closed off. We have been here 29 years, we've seen lots of excitement but I thought it was getting better actually."
Korbay Kaner, owner of Kem Off Licence on Haggerston Road, told the Press Association he heard shots.
"All we heard was the couple of shots," he said, adding that one of his customers saw what happened.
"They were chasing a couple of people. One of them stopped, turned around and shot the police officer," he said.
Mr Kaner said the police had been raiding a property nearby, and said the shooting took place in the middle of Haggerston Road.