Firefighters in south China's Guangdong Province began to clear up the debris as explosions caused by fireworks stored in 20 warehouses in Foshan City stopped by 10 a.m. on Friday.
Five people, including four warehouse guards, were questioned by police in connection with the incident, said a spokesman for Foshan's Sanshui District Communist Party of China (CPC) committee.
The blasts started around 3:30 a.m. on Thursday at the No. 7 building of the Yuetong Warehouse and Transport Co., a private firm based in Sanshui, on the northern bank of the Pearl River.
Only two people suffered slight bruises from broken glass.
The blasts set a neighboring woods on fire, an official with the Foshan government said.
Windows were shattered and metal doors were damaged up to a kilometer away, and steel structural debris from the warehouses was found close by. Many residents said they thought the area had been hit by an earthquake.
Liang Gan, Guangdong Provincial Bureau of Seismology deputy director, said the fireworks explosion produced the energy equivalent to a 1.1 degree tremor on the Richter scale.
"The explosion didn't cause any damage to the geological structure and therefore was definitely unable to lead to a full-size earthquake," Liang said. "So there is no need to panic."
Fang Gengming, Sanshui District work safety bureau head, confirmed the explosions started bush fires on nearby hills, but declined to give more details of the damage.
To expel panic among residents, the seismic authority in Foshan sent text messages to explain the situation to the general public shortly after the explosions happened.
About 200 migrant workers and nearby residents were evacuated from their homes. More than 650 police, fire-fighters and soldiers rushed to the site, but were driven back by the blasts.
Guangdong has banned production of fireworks in the province. The Yuetong Warehouse and Transport Co. is said to handle 60 to 70 percent of China's exported fireworks, most of which are made in neighboring Hunan and Jiangxi provinces.
Investigations into the cause of the explosion and an assessment of the damage are underway.