Eight people faced terror when a helium balloon at Ocean Park sprang a leak and plunged about 60 meters to earth.
The worst accident since the park opened at Aberdeen 35 years ago left five visitors injured or in shock, though none were hurt seriously. Four had been in the balloon and a fifth on the ground.
Seven park visitors and the operator had been in the SkyStar ride when the balloon failed at 3.45pm yesterday.
After treatment for the balloon riders at the scene, two women with hand and leg injuries were taken to Ruttonjee Hospital in Wan Chai. They were allowed to leave after further treatment.
But a fifth casualty, a visitor on the ground who was hit by the falling balloon, was taken to Queen Mary Hospital in Pok Fu Lam with head injuries.
"It happened so quickly," one casualty said. "I didn't even know what was happening. One moment we were up in the air and the next we hit the ground."
Government and Ocean Park engineers were soon investigating at the scene. Park chiefs must make a report to the government within a week.
But Ocean Park engineering executive director George Tso Chi-keung offered some immediate findings.
The operator in the balloon realized there was a leak from readings on the helium gauge in the steering compartment, he said.
"Normally, it would fall gradually from a height of 60 meters. However, when it was about 20 meters from the ground it fell quickly - faster than the normal 0.6 meters per second."
The problem was a rupture in the gas-filled bag. Park officials refused to provide details, but some witnesses said the gash was more than three meters wide.
Ocean Park deputy chief executive Matthew Li Sing-chung said the balloon landed on a pedestrian walkway instead of its pad because of the leakage and wind. Other people talked of it hitting a tree and landing near a fountain.
Li also said there had not been an announcement in the park about the plunge, though "we immediately notified the Electrical and Mechanical Services Department about the incident."
He added: "We were not trying to hide the truth. Our immediate concern was to take care of the injured."
Several visitors said the incident did not put them off the idea of returning.
A 17-year-old named Lau was there with two friends for a birthday celebration. They were in the aquarium near the SkyStar when the fall came, but "we knew about the incident as our friends called to us." They'd return, he said.
The SkyStar has been in operation since 2007. The balloon is 22m in diameter and 34m in height. It can carry up to 30 people.
It is popular for its place in a carnival setting with clowns, jugglers and acrobats. It can rise 100m to provide a majestic view of southern Hong Kong.
A detailed weekly check on the balloon on Tuesday did not show anything amiss. And the daily check did not show up any fault.
Hong Kong Polytechnic University mechanical engineer Lo Kok-Keung said the park is fortunate to have escaped a disaster.
"It's lucky there was still helium in the balloon. If there no helium it would have fallen at a speed that could probably have killed everyone on board."