Drones worth $100k plunge into river as 'technical issues' hit Perth Christmas event

A review is under way after a futuristic Christmas celebration in Perth went wrong when 50 drones, worth roughly $100,000, plunged into the Swan River.

The City of Perth blamed '"technical issues" for the mishap at the city's Summer Nights City of Lights event on Sunday night.

As drones drew colourful festive scenes in the sky, some started dropping to the earth.

READ MORE: Two children 'seriously burned' in Sydney school explosion

Roughly 50 of the 500 aircraft, each costing about $2000 according to the drone company, dropped into the river.

City of Perth lord mayor Basil Zempilas admitted "some of the drones weren't doing what they were supposed to" but said there was no risk to the public.

"I accept that the drone show on Sunday night fell short of expectations," he said.

"That was because of some technical issues."

READ MORE: Three states issued stark warning over 'damaging, vigorous' system sweeping nation

He said Civil Aviation Safety Authority safety protocols were observed and nobody was in danger.

"The drones that fell fell into the river and nowhere near people," he said.

"There is a reason why there is such a strict enforcement of the safety zone around this technology.

"Things can go wrong with technology of this kind."

A review is underway into what happened, and the missing drones will be retrieved from the river.

Drone Sky Show managing director Joshua Van Ross said each drone cost about $2000, making the mishap worth around $100,000.

"This technology is still evolving," he said.

READ MORE: Serial rapist known as 'Bondi Beast' identified with DNA technology

"I did cry a little bit last night, I am trying not to think about it. It was an expensive show for us."

He said wind can cause things to go wrong, and it is normal for two-to-three drones not to work properly.

He said they were looking into what had gone wrong.

Computerised drones are becoming an alternative to fireworks.

The show aimed to tell the story of a 'Christmas in the City', and is part of six planned over the summer, to "wow the people of Perth," the Council says on its website.