BEIJING — An explosion in a factory zone in northern China late Tuesday killed at least 23 people and left 22 others injured, officials said, adding to the string of deadly accidents in the country’s vast industrial sector.

The explosion erupted near the Hebei Shenghua Chemical Industry Company plant in Hebei Province and tore through roughly 50 vehicles, including 38 trucks that had lined up to deliver chemicals and other goods to factories in the zone, Chinese news reports said, citing investigators. But later on Wednesday there was still no firm answer on what caused the explosion, and whether there was any link to the big Shenghua plant or maybe a smaller factory nearby.

The fiery explosion could be heard from over a mile away, news reports said, citing residents, and video and pictures from the scene showed that the blast sent a dark plume of smoke into the night sky. Daylight arrived to reveal charred, smoldering trucks, some with their tires burned away, that lay along the road.

After decades of encouraging feverish industrial growth, the Chinese government has been trying to curb the large numbers of accidents in factories, mines and plants. Official statistics indicate that industrial accidents and deaths have fallen.