A man remains in custody on suspicion of the attempted murder of a detective following an undercover police operation yesterday.
The 31-year-old is also being held in connection with the possession of a firearm and is in custody at a north London police station.
The officer, part of the Metropolitan Police's Trident gun crime unit, is currently recovering in hospital having been shot in the shoulder during the attempted raid in a residential part of Hackney, east London. His condition is described as stable.
Senior colleagues have paid tribute to the detective's bravery.
Commissioner Sir Bernard Hogan-Howe, Britain's top policeman, said: "This officer has shown great bravery. His colleagues have described him as 'exceptional' and 'professional'. He has been that and more.
"I am of thinking of him and his family and I wish him a quick recovery.
"Our officers confront danger every day. I am proud of all of them and the courage that they show."
Commander Duncan Ball said he was unable to state for operational reasons whether any shots were fired by police during the incident, at around 12.45pm.
But he praised the "tireless" actions of police which he said demonstrated officers' selfless dedication to duty.
He said: "This incident reveals the very real risks our police officers face on a day-to-day basis while protecting the safety of Londoners."
Locals said the officer was chasing suspects fleeing the raid when one of them turned around and shot him.
Residents said Clarissa Road in Haggerston was lined with undercover police in cars when at least two shots rang out.
Business owner David Salvester, 28, heard one plain-clothes officer shouted: "Nick's been shot."
Mr Salvester said: "We were in the house and we heard a bunch of yelling. We went outside and there was a bunch of officers in green with their dogs.
"They had helmets and machine guns, I think. That's the point we heard the gunfire. They were all scrambling about. It was two shots, I think.
"The whole road was filled with undercover police. They all burst out of their cars (when the shots went off). Then there was a woman shouting, 'Nick's been shot, Nick's been shot'.
"She started getting all her first aid stuff out of the car. She was calling out a lot.
"There was obviously some kind of raid."
Kaner Korbay, who owns a nearby dry cleaners, said: "There was a raid on a house in Scriven Street, they tried to get away and the police were chasing them.
"One of them shot the policeman. Right in the middle of the street. Within 30 seconds the police were everywhere, blocking the road."
The Met Police said officers from its specialist firearms command (SCO19) and Trident area crime command had been taking part in an "authorised firearms operation" when the shooting happened.
Police are investigating the circumstances.