About 90 drones plummeted from the sky above Sydney’s Darling Harbour during an aerial drone show, prompting a second Vivid event to be cancelled.

Vivid Sydney said “unforeseen technical difficulties” occurred during Monday’s 7.30pm performance, called Star-Bound, resulting in 83 drones falling into the water at Cockle Bay in Darling Harbour and six landing on a boardwalk. No injuries have been reported.

Skymagic, the UK-based operator of the drone show, said in a statement that an “unforeseen change in the radio frequency environment occurring after take-off” compromised the positional accuracy of the fleet.

“Early indications show there was no foul play present, but we are still investigating all possibilities,” Dyfan Rhys, Skymagic’s head of operations and production, elaborated on Tuesday.

Rhys said despite the dramatic images circulating on social media, the public was not at risk.

While the pilot team managed to lock the main fleet stationary in the air to evaluate the situation, the drones experiencing issues encountered the geofence boundary.

“[They] shut down to preserve the safety zone,” he said, resulting in 83 falling into the harbour and six landing on the foreshore boardwalk.

Four performances were cancelled on Tuesday and Wednesday as a precaution while operators complete a full technical and safety review.

The chief executive of Destination New South Wales, Karen Jones, issued an apology to the thousands of spectators who had gathered around the waterfront to watch the show.

“We apologise for the disappointment, and also for inconvenience caused to all attendees,” she said, adding that a full safety assessment was being undertaken as a precaution.

“The next program to do the drone show is for Sunday night,” she said, “I can’t guarantee that that will go ahead. It does depend on the outcomes of this assessment.”

Vivid said in a statement Monday night that “public safety and security remain the absolute priority”.

“We apologise for the disappointment and thank everyone for their patience and understanding,” Vivid’s statement said.

Jones told ABC Radio Sydney while it was “incredibly upsetting” the shows had been cancelled, safety protocols worked as planned.

“There was an exclusion zone that was specifically designed for the drone show and it did mean that if there was a technical failure – which there was last night – it meant that the drones either fell into the water or within that exclusion zone,” Jones said.

The Australian Transport Safety Bureau said it has been notified of the incident and was gathering more information.

Star-Bound is scheduled to run Sunday to Wednesday evenings at 7.30pm and 9.30pm for the duration of the festival, although the Vivid website notes the performances depend on the weather.

The drone show was scrapped last year amid concerns over crowd control issues but it returned this year heralded as Australia’s “most extensive” event of its kind. It features 1,000, purpose-built drones made specifically for large-scale aerial displays.

In 2023, more than 400 drones fell from the sky into Melbourne’s Yarra River during a light show celebrating the Matildas before the Women’s World Cup, with an ATSB investigation later finding wind conditions were to blame.