An explosion at a fireworks factory killed at least 13 people and injured 148 in Northeast China's Heilongjiang Province on Monday, local authorities said.

The explosion occurred at 9:40 a.m. at a factory owned by Huali Industry Corp. in Wumahe district, Yichun.

The fire was extinguished after a helicopter dumped water on the blaze but some fireworks were still exploding, officials said.

Firefighters are still working to control and prevent the two warehouses, where a lot of explosives are stored, from exploding.

The explosion shattered the windows of almost all the buildings within a km and the shockwave of the explosion was felt up to 5 km, Xinhua reported.

More than 1,700 firefighters and soldiers and 62 fire trucks were dispatched to the scene.

Hundreds of rescuers and medical staff were also mobilized to search for and treat survivors.

As of 3 p.m., 22 injured people were hospitalized.

The local government did not release the exact number of workers who were in the factory when the explosion occurred.

More than 2,000 residents were evacuated after the blast.

The cause of the accident is still under investigation.

The factory was not under production when the explosion occurred. Instead, workers were packing the inventory, Zhao Weiqiang, deputy head of Wumahe district, told reporters on Monday.

"I was in my office when I heard a deafening sound at about 9:30. All the windows of the office shattered at once. We were all frightened," an employee at a nearby furniture factory told China Daily.

"We assumed it was an earthquake because the office building trembled and the lamps and clocks fell."

The employee said her factory is located about 300 meters away from the site of the explosion.

"We all ran out to the open area in front of the office and found that all workers in our factory had already come out.

"A huge black mushroom-like cloud was visible. It rose and grew from where the fireworks factory is located," she said.

(China Daily August 17, 2010)