A suspected armed robber has died in hospital after being shot by police in Kemp Town, Brighton.
The Independent Police Complaints Commission has said a gun was found at the scene.
It also said the shooting took place after a pre-planned police operation related to a number of armed robberies in Brighton, Hove and mid-Sussex.
The man, who was in his 40s and has not yet been formally identified, died at the Royal Sussex County Hospital after the shooting in Rock Place this lunchtime.
A statement from the IPCC said: "The Independent Police Complaints Commission is independently investigating the fatal shooting of a man by police in Sussex.
"Armed officers were deployed to the Kemp Town area of Brighton at around lunchtime today, Thursday 10 February 2011, as part of a pre-planned operation in relation to a number of armed robberies in the Sussex area.
"Just after 1pm this afternoon, a man was shot in Rock Place, Brighton. He was taken to hospital but was pronounced dead a short time later.
"What appears to be a black handgun has been found at the scene.
"This will now be examined to establish whether it is real or an imitation weapon and whether it had been fired."
IPCC Commissioner Mike Franklin said: "IPCC investigators are currently in Sussex carrying out enquiries to establish exactly what happened in this case.
"This will involve taking initial accounts from those officers involved to establish which officer or officers fired and why, as well as identifying evidence on police systems such as incident logs and radio transmissions.
"We will be working to identify independent witnesses who saw any part of today’s incident as it unfolded, as well as to gather CCTV in the area which may have captured events.
"Our investigators will also look at the pre-planning of the operation itself.”
The man has not yet been formally identified.
Frankie Sparrowhawk, 18, said he walked outside just as the man was being shot.
He said: "I heard two gunshots and saw someone lying on the floor. There were five or six police officers there at that point.
"I was too far away to see if he was moving but it looked like one of them was trying to resuscitate him.
"An ambulance arrived within about two seconds."
Local resident Janet Hood, 67, said she was not able to get to her ground-floor flat in the street.
She said: "I wasn't in, luckily.
"I'm quite frightened and a bit shaken-up to be honest.
"I only know the neighbours to say hello to but it's usually a very quiet street, we don't usually have any trouble here."
The incident has been referred to the Independent Police Complaints Commission, which has confirmed it is sending its own investigators to the scene.
An area of the seafront near Lower Rock Gardens has been cordoned off and officers from around the city called in for the operation.
Motorists have been warned by police that a number of roads in the area, including a section of the A259, are currently closed and likely to be so for the approaching rush hour.
Drivers are advised to avoid the area if possible.
Students at the Brighton Institute of Modern Music on Rock Place have been ordered to stay inside their classroom by police.
Cathryn Craddock, head of creative and music said: “We were lucky that most students had left their morning classes before the shooting happened. But it’s still worrying. The principal is down there.
"Police have told all students and teachers to stay inside until further notice.”
Carla Ter Matt sales and marketing manager at Drakes Hotel on Marine Parade said: “The cordon is down Rock Place but stops at the edge of our building. We are checking guests in and the police have told us there is no danger.”
Anybody who witnessed the shooting is asked to contact the IPCC on 0800 0969075 or email email@example.com.
Last November, an inquest ruled that Sussex police officers acted lawfully when they shot dead gun enthusiast Mervyn Tussler.
Mr Tussler, 64, suicidal after being told he could not look after his sick wife Winifred, pointed an antique Colt 45 handgun at a manager at his sheltered accommodation, sparking a three-hour standoff with armed police in May 2009.
In January 1998, Sussex Police shot dead James Ashley while naked and unarmed at his Hastings home.
The officer who fired the fatal shot, PC Chris Sherwood, was tried for murder and manslaughter and acquitted.
Last year, his family accepted undisclosed damages after Sussex Police admitted negligence.
Did you see what happened? Call The Argus on 01273 544520 or leave your comments below.