According to Facebook page Singapore Incidents, which cited a netizen called Chaotic Panda, there was an alleged 6-hour stand-off between the authorities and 3 alleged drug suspects.

Firefighting vehicles from the Singapore Civil Defence Force (SCDF) and police vehicles were seen at the site, parked at an open carpark in the area.
Unidentified personnel were also seen in the open area between two HDB buildings.

Police officers were also seen walking into a HDB block, along with two men who were carrying bags of unidentified gears and equipment.

The SCDF’s air pack was also seen deployed at the foot of the HDB building, and a drone was also seen flying overhead in the air.

SCDF personnel were also seen inside a couple of HDB units with the windows open, and a net was also deployed, covering a unit that was between them.

At the time of writing, not much information regarding the incident has been revealed (yet), save for online chatter and alleged presumptions.
Stay tuned to this page for more updates.