The explosion was triggered by self-ignition of 'waste' explosives but no casualties were reported in the incident.
Blast occured at around 8:03 am (local time) in the 'waste explosive warehouse' on the sixth floor of the building, housing the Public Security of Bureau of Qingtian County in Zhejiang province, informed the local police.
The windows of the building were shattered during the explosion, apart from the huge bangs.
The waste explosives were confiscated earlier by police. Police is still investigating the reason of the explosion.