Do not be alarmed. On Thursday, 15 February 2018 at 6.20pm, SCDF will be sounding the “Important Message” signal through the island-wide Public Warning System (PWS) sirens and the SGSecure Mobile App.
Tune in to any local radio station for a brief message on the PWS immediately after hearing the signal.
You can also find out more about the PWS by visiting www.scdf.gov.sg
Source: FB post by Singapore Civil Defence Force