(the actual 'silence', marked by carhorns and air sirens, starts at around 01:20 in the video)

China on Monday began a three-day national mourning for the tens of thousands of people killed in a powerful earthquake which struck the country's southwest on May 12.

At 4:58 a.m., the national flag at the Tian'anmen Square in downtown Beijing flew at half-mast after a complete flag-raising ceremony.

All national flags will fly at half-mast at home and Chinese diplomatic missions abroad from Monday to Wednesday. Public recreational activities will be halted during the mourning period.

At 2:28 p.m. Monday, Chinese citizens nationwide will stand in silence for three minutes to mourn for the victims, while air raid sirens and horns of automobiles, trains and ships will wail in grief.