Air defense alarms will be sounded across Shanghai on September 20, the 25th National Defense Education Day, to raise national defense awareness, local authorities announced on Friday.

The alarms will take place from 11:35am to 11:58am throughout the city, except for areas around Pudong and Hongqiao international airports.

Pre-alarm will be sounded three times from 11:35am to 11:38am, each lasting for 36 seconds and followed by a pause of 24 seconds.

Air raid alarm would be raised 15 times from 11:45am to 11:48am, with each sounding for 6 seconds and followed by a 6-second pause, taking up a total of three minutes.

All-clear alarm will sound from 11:55am to 11:58am, continuing for the full 3 minutes.

Except for those residents assigned to participate in drills or related events, other locals should refrain from taking any action upon hearing the alarms.