AMPANG, Oct 13 — The balloon explosion that injured 16 people at a fitness event in Putrajaya yesterday may have been caused by a mixing of gases, Datuk Seri Dr Wan Azizah Wan Ismail said.

The deputy prime minister noted that helium typically used for balloon inflation was inert and may have been combined with a flammable gas, possibly to reduce costs.

"This can cause all kinds of problems. If you are aware there is flammable gas or substances nearby, do not use a live flame near it,” said Dr Wan Azizah, who is also the women, family, and community development minister, during the National Sports Month celebration for the Hulu Langat District at Pandan Indah.

Of the victims, she said three adults and a child may be discharged after the doctors’ examination of their burn wounds.

"Two other patients have also been stabilised but require further treatment, as their wounds are deeper and require more dressing and cleaning in the ward.

"The Social Welfare Department will provide psychological support, particularly for the child victims who are quite traumatised by the incident,” Dr Wan Azizah said.

The incident occurred late yesterday morning as the Education Ministry-organised event was wrapping up, when someone attempted to sever the string tying the balloons together with a cigarette lighter.

Sixteen people — seven of whom were children — were caught in the blast. Five people sustained second degree burns as a result.