Just after midnight yesterday, Singapore Civil Defence Force (SCDF) emergency responders were seen racing into Compass One shopping mall.
"Shoppers" at an event held at the mall's atrium had "collapsed" after feeling unwell, and as the rest of them ran out of the building in a panic, several were "injured" in the process.
But officers arrived at the scene and quickly evacuated the "casualties", while others used HazMat (hazardous materials) detectors to swiftly locate the source of the "chemical release".
The SCDF yesterday gave the public a closer look at one of its live exercises through several posts on its Facebook page from 12.30am to 3am.
Such exercises are part of the SCDF's ongoing efforts to validate and update its operational plans and procedures, it said.
Emergency vehicles involved in the exercise had their beacon lights switched on to alert motorists, and signs were placed in the vicinity of the mall to inform the public of the exercise, it added.
At about 2am, the SCDF said in a post that HazMat specialists decked in orange suits had found the source of chemical release near the atrium, which resulted in the shoppers collapsing.
The HazMat specialists took samples of the chemical for identification and began mitigating its harmful effects.
Meanwhile, casualties who were evacuated were put through the decontamination process.
In a video, rescuers from the SCDF Special Rescue Unit were seen tending to them at the Mass Decontamination Vehicle, which is purpose-built to accommodate a higher capacity of casualties exposed to chemical agents.
Once the casualties were cleared of contaminants, officers provided medical assistance at the on-site first aid point, as seen in a series of photos shared by the SCDF.
Others who required further medical help were taken to hospitals via ambulances, said the SCDF in its last update of the exercise.
Such exercises were previously conducted in Nex mall in Serangoon, One Marina Boulevard, and Selegu Tower on Sentosa, among other locations across Singapore.