A sound operator on reality TV show Cops has been shot dead by police officers who opened fire during a robbery at a fast food restaurant.

Bryce Dion, 38, died along with the robbery suspect, who was armed with a pellet gun police thought was a real weapon, authorities in Omaha, Nebraska, said Wednesday.

The suspect, 32-year-old Cortez Washington, fired from the pellet gun before officers returned fire, police chief Todd Schmaderer said. He said witnesses and officers thought the Airsoft handgun looked and sounded real, but later discovered it fired only plastic pellets.

Cops has depicted law enforcement officers in action since it premiered in 1989. The show has been filmed in at least 140 US cities and three foreign countries, its website says.

Washington was wounded by the officers' gunfire, but fled outside the Wendy's restaurant before collapsing. Officers continued firing as he left the restaurant and that was when Mr Dion was hit, said Mr Schamaderer.

Mr Dion was wearing a bulletproof vest, but a single bullet that hit his arm "slipped into a gap in the vest" and entered his chest, the police chief said.

"My concern with my officers is that they are taking this very hard," Mr Schmaderer said. "Bryce was their friend."

Video captured by the cameraman who was with Mr Dion shows the chaotic situation in the restaurant. Police released still shots from the video showing a hooded and masked person pointing what looks like a gun at police. Mr Schmaderer said police would not release the full video, but it would be part of the grand jury investigation into the shooting.

Mr Schmaderer said Washington had a lengthy criminal record, including an accessory to robbery conviction from Missouri for which he was on parole. He moved to Nebraska in September 2013, and his parole was due to expire in June 2017.

The incident began when one of the officers, on his way to another reported robbery, called to request back-up for the hold-up at the Wendy's restaurant. The Cops crew members were with two officers who responded to that request.

When police entered the restaurant and confronted the suspect, Mr Dion was separated from the cameraman, Mr Schmaderer said.

Langley Productions said this was the first time one of their crew members had been fatally shot while filming. The show started on Fox in 1989 and is now shown on the Spike network.

In 2010, a TV crew for the A&E reality show The First 48, recorded a Detroit police raid in which a seven-year-old girl was accidentally killed by an officer. That incident highlighted concerns about whether TV cameras influence police behaviour, perhaps encouraging showboating.

But Mr Schmaderer yesterday bristled at a reporter's question about whether his officers overreacted, knowing that cameras were recording them, calling the suggestion "absolutely ridiculous". He said the video of the shooting showed the officers reacted properly.

Mr Schmaderer said he accepted the invitation from Cops to film in Omaha in the name of transparency, but also expressed regret at the outcome.

"Personally, I will live with this forever," he said. "If I'd have known that this would happen, of course, I wouldn't have done it."

Langley Productions president John Langley and his son, executive producer Morgan Langley, said police had acted professionally.

John Langley said the crew had been filming all summer in Omaha and had only one week left when the deadly shooting happened.

"Bryce has been with us for seven years," said Morgan Langley, who hired Mr Dion. "This is very hard for us."