More than a hundred people were evacuated from Sim Lim Square yesterday after the contents of a rubbish bin on the fifth floor caught fire and set off the building's sprinkler system.

The Singapore Civil Defence Force (SCDF) responded to the incident at noon, a spokesman said.

"About 150 people were evacuated from the premises by the in-house Company Emergency Response Team prior to SCDF's arrival."

The fire was extinguished using a hose reel and there were no reported injuries, he said, adding that the SCDF is investigating the cause of the fire.

Undertaker Loh Yan Long, 33, was walking by the building during his lunch break when the incident occurred.

"I observed more than a hundred tenants and shoppers exiting the building. There was no visible smoke anywhere outside, as the fire had occurred inside. The SCDF was also present by the time I was returning from my lunch," Mr Loh said.

Videos shared with The Straits Times show smoke in the corridors of Sim Lim Square.

When ST reached the building at around 4.30pm, tenants of the two stores closest to the fire were cleaning up.

A electronic store salesman, who wanted to be known only as Patrick, said he had seen a large cloud of smoke coming from the doorway towards the fire service lifts at about 11.30am.

An elderly cleaner who was nearby went to investigate but emerged from the area moments later, saying he was unable to proceed as the smoke was choking him.

Almost immediately after, the smoke triggered the building's fire alarm.

Patrick said he returned to find the floor of the shop covered by water.

"On a usual day, we might make $1,000-$2,000, but the whole of today was spent dealing with the situation and clearing up the mess," Patrick said.

He was also worried the electronic products in his store might have been damaged.

Building manager Jeffrey Zhou told ST that the water came from the building's sprinklers.

An accounts personnel of a neighbouring store, who gave his name as Cloud, 37, said the evacuation lasted until around 3pm.