Five people have been detained for connection with a deadly blast Saturday in Xiaogan City of central China's Hubei province, local police said Tuesday.

They were detained on the crime of causing an accident with dangerous substances, police said, adding the five people were found to have transported explosives illegally.

The five detained included two drivers of the truck surnamed Liu and Wu, gunpowder owner Zhang Pingyuan and sellers of the explosives surnamed Zhang and Xie, according to police.

The truck was carrying 18 tonnes, not five tonnes as claimed by Zhang Pingyuan, of gunpowder when it exploded at about 12:20 a.m. at a section of the Beijing-Zhuhai Highway in Xiaogan City, leaving four dead and 29 others injured, the spokesman said.

Six of the injured had been discharged from hospital, he added.

The four killed were on another truck carrying pepper.

Repair has been completed on 350 buildings of the 2,096 houses damaged by the blast and further support for the victims is underway, according to a spokesman with the municipal government.

The highway is fully repaired Tuesday.

Traffic resumed on the highway at 2:38 p.m. Sunday after a 10-meter long and 1-meter deep crack was filled up.