Putrajaya district police chief ACP Rosly Hasan said the police had opened an inquiry paper into the incident which occurred during the education ministry’s 2019 National Sports Month event.

“They were filled with hydrogen, not helium. Hydrogen is highly sensitive and extremely flammable,” Rosly said in response to the case.

Previous reports said the balloons were filled with helium gas.

The incident is believed to have occurred when someone tried to sever the string tied to a bunch of balloons with a cigarette lighter, the flame of which struck one of the balloons before the whole bunch exploded.

Rosly said police had also found a cigarette lighter at the scene, although the suspect has yet to be identified.

On the latest status of the victims, Rosly said as of 10am today, two men and two women were still receiving treatment for second-degree burns at the Putrajaya Hospital. They were among six victims, including an eight-year-old girl, admitted to the hospital after the incident.

Ten others received out-patient treatment.