Selangor fire and rescue department director Wan Razali Wan Ismail said the state operations centre received a report at 11.23am.

“Six officers from the KLIA fire and rescue department and a hazardous material (hazmat) team from the Shah Alam fire and rescue department were sent to the location,” he said in a statement today.

KLIA police chief Azman Shari’at said the gas leak came from an skid tank, left unattended for nine years. The leak was caused by a faulty valve.

He said the gas has been identified as methyl mercaptan or methanethiol (a colourless flammable gas that smells like rotten eggs or rotten cabbage).

Azman said exposure to methyl mercaptan is not fatal but causes nausea, vomitting, dizziness and headache.

He said KLIA was safe from any threat of disaster and advised the public not to be alarmed.

Azman said Gas Malaysia was taking action to close the leak. The skid tank will be removed and sent to a disposal site after the leak is patched up.

About 1,000 people, mostly from Malaysia Airlines Engineering and MAB Academy, were evacuated from the cargo terminal area following the gas leak.

Following the gas leak, 39 victims were rescued with most of them treated at the location while 14 were taken to the KLIA Air Disaster Unit while one victim was sent to the Putrajaya Hospital for treatment.