Vehicles plummeted about 100ft to the ground after the blast, state-run China Central Television reported. It said at least 11 people had been injured, though the search for bodies continued yesterday.
The official Xinhua News Agency said the falling concrete smashed and buried at least 25 vehicles. Rescue work continued to recover bodies yesterday.
Local media said that the lorry that exploded had taken to the road without proper registration and had false papers, claiming it was transporting general merchandise. It said police had detained four suspects but did not provide further details.
Preliminary investigations blamed the collapse of the elevated road on the blast, according to a statement by the provincial government of Henan. A 260ft (80m) stretch of the road in the province’s Mianchi county collapsed, scattering blackened chunks of debris and shattering the windows of a nearby service station.
A lorry driver interviewed on China Central Television said he was only 60ft away from the explosion.
“I heard a huge bang and immediately braked. I saw small fireballs falling down one by one,” said the unidentified driver, whose lorry’s windshield was smashed by the blast wave.
Photographs posted online by Xinhua News Agency showed a whole section of the elevated motorway missing, with one lorry’s back wheels perched at the edge of a shorn-off section of road.
Other photographs showed firefighters below spraying water on scorched blocks of concrete, wrecked lorries and flattened freight containers.
There was no immediate word on the cause of the explosion, which occurred about 55 miles (90km) west of Luoyang, an ancient capital of China known for grottoes of Buddhist statues carved from limestone cliffs.
Fireworks are an enormously popular part of the Chinese celebrations for the lunar new year. To meet the demand, fireworks are made, shipped and stored in large quantities, sometimes in unsafe conditions.
A result of this is occasional catastrophes.
In 2006, on the first day of the lunar new year, a storeroom of fireworks exploded at a temple fair in Henan, killing 36 people and injuring dozens more.
In 2000, an unlicensed fireworks factory in southern China exploded, killing 33 people, including 13 primary and secondary school pupils working there on a seasonal basis.