XI'AN - Police have detained four people over a truck explosion that caused 10 deaths and a viaduct collapse in Central China's Henan province, government authorities confirmed on Sunday.

Investigations found that the fireworks the vehicle was carrying were produced by a firm registered in Pucheng county of Northwest China's Shaanxi province, said the press office of the county government.

The four people detained by police for further investigation are from the fireworks producer and the haulage company that owned the truck, said the office.

The company, Pucheng Hongsheng Fireworks Ltd., is a licensed fireworks producer with a safety production license, according to investigators.

The blast, which occurred around 9 am on Friday, caused the collapse of a 30-meter-high expressway viaduct in Mianchi county, Sanmenxia city, about 193 km west of the provincial capital of Zhengzhou.

Ten people were killed and another 11 injured in the accident.

The driver of the truck, a man surnamed Shi, set off in the vehicle, which was carrying about 600 large bags of fireworks, from Pucheng on Thursday.

Rescue work has concluded, with the 11 injured people all in stable conditions. The probe into the accident is continuing, according to government sources.