A tanker is alleged to have dumped the chemical waste in Sungai Kim Kim, causing the leak.

The victims are students and canteen workers of SMK Taman Pasir Putih and SK Taman Pasir Putih, aged between seven and 40.

Nineteen were sent to Hospital Sultan Ismail (HSI), two to Hospital Penawar and seven to the Pasir Gudang public clinic.

“Eight of those at HSI are in critical condition and in the Red Zone and the rest are in the Yellow Zone,” Johor Health, Environment and Agriculture Committee chairman Sahruddin Jamal told reporters at an operations centre set up outside SMK Taman Pasir Putih.

He said the Environment Department and the Johor Fire and Rescue Department were investigating a report that a tanker had dumped chemical waste in Sungai Kim Kim yesterday morning.

“The situation is under control and there is less smell of the gas. However, anyone showing symptoms like nausea and throat irritation must go to a hospital as quickly as possible,” he said.

Zone 1 Fire and Rescue Department deputy chief Lokman Hakim Sulaiman said they received a gas leak and chemical spill report at 5.15am today.

“After detecting methane in the air, we ordered an evacuation of anyone within a 500m radius of the source of the leak,” he said.

Johor Fire and Rescue Department director Yahaya Madis said oil booms – floats that can absorb and check chemical pollution from spreading – would be used in the section of Sungai Kim Kim where the leak occurred.

‘’The pollution covers an area within a 500m radius of the river,’’ he told reporters.

Yahaya said 30 officers and firemen were sent to the scene after the department received a call from a resident of a nearby housing estate at 5.15am.