BEIJING -- Authorities in north China's Hebei province have ordered all fireworks factories to halt production following an explosion which killed at least 29 people and injured more than 100, state media said Wednesday.

The factories are required to remain shut until they pass safety inspections, the China Central Broadcasting Station said.

The blast Monday evening in Guoxi village killed 29 people, including the factory manager, and injured more than 100, state media said.

Around 169 people were working at the time and only 30 of them escaped when the factory collapsed, the radio station said.

An official in charge of work safety in the provincial capital Shijiazhuang told AFP Wednesday rescue crews had finished sifting through the rubble and had retrieved all the victims buried.

"The deaths won't increase by much. The cleanup work at the scene has been completed," said the official, surnamed Zhang. "Seventy-one people are still in hospital."

Many of victims have serious injuries, including severe burns, hospital officials said.

The Xinhua News Agency attributed the cause of the blast to heat-induced ignition of gunpowder following several days of unusually hot weather.

The radio station said the blast happened after workers took the gunpowder outdoors to dry under the sun because it was damp and lumpy, causing the explosives to ignite in the heat.

The force of the explosion was so strong that it partly destroyed an office building more than 100 meters (330 feet) away while cars and motorcycles were set alight, the China News Service said.

Residents up to three kilometers (1.86 miles) away told AFP they heard the explosion.

The village clinic could not handle the large number of casualties and had to send victims to at least six hospitals, some of them in the provincial capital some 60 kilometers (37.2 miles) away.

The factory was built in 1984 and had employed 220 workers, the radio station said.

Hebei Province's Communist Party Committee, Propaganda Department and other government offices refused to reveal any information, only saying that the provincial party secretary and governor had traveled to the scene to "personally direct" rescue work.

China is the world's biggest producer of fireworks, and the industry largely relies on manual labor from people in rural areas who work in unsafe conditions either at home or in small and poorly monitored factories.