A collapsed section of a highway is seen near Meizhou, in southern China's Guangdong province, May 1, 2024. [AFP]

Chinese officials say the death toll from a collapsed highway in southeastern Guangdong province rose to 48 on Thursday, some 24 hours after a section of the four-lane mountainous pass buckled in the wake of record rainfall and flooding, sending 23 vehicles tumbling down a steep slope with some bursting into flames.

Three people remained unidentified, pending DNA testing, according to a local official in Meizhou City. It was not immediately clear if they died, which would bring the death toll to 51. At least 30 other people had non-life-threatening injuries.

The collapse occurred on one side of a four-lane highway in Meizhou about 2 a.m. Wednesday, just as China kicked off a five-day holiday.

For a second day, rescuers searched for trapped people by digging through mountainous terrain. Construction cranes lifted out burnt-out and mangled vehicles.

Heavy rains, the risk of secondary disasters and the large number of trapped, burned and buried vehicles were complicating rescue efforts, a city official said. More than 570 people and 80 rescue vehicles have been deployed to help with the mission.

Meizhou is one of the areas in southern China's Guangdong that has been overwhelmed by heavy rain since last month. The adverse weather triggered dangerous mudslides, inundated homes and destroyed bridges.

The rain saturated soil in the area, “making it prone to secondary disasters during the rescue process,” said Wen Yongdeng, the Communist Party secretary for the Meizhou emergency management bureau.

Over the past two weeks, parts of Guangdong experienced record rains, hail and flooding. A tornado killed five people in the provincial capital during storms last weekend.