At least 39 people were killed after a tornado, hail storms, gale-force winds and torrential rains hit southern China, damaging thousands of homes and destroying crops.

The storms hit the giant southwestern municipality of Chongqing as well as neighbouring Guizhou and Hunan provinces overnight, leaving more than 190 people injured and at least six missing, state press and officials said Thursday.

State television showed collapsed homes, uprooted and downed trees, landslides and partially flooded roads in Chongqing, where 29 died and more than 70,000 people were displaced, according to the civil affairs ministry.

The death and injury tolls from the storms rose throughout Thursday, as officials worked to tally the total number of dead and injured, as well as the number of homes damaged.

"Tornados never happened here in the past -- this is the first time," Liu Fang, a local township official in Liangping county, one of the hardest-hit areas in Chongqing, told AFP by phone.

"So far, six have died and 38 are injured in our township. The electricity has been cut, and some houses were damaged due to the strong wind."

The injured were being brought to local hospitals while tents were being set up for those whose homes were destroyed, Li said.

Up to 157 millimetres (more than six inches) of rain had fallen in parts of the region -- stricken by a severe drought since last year -- from late Wednesday to Thursday afternoon, the China News Service said.

The storms were caused by a heat wave from the south colliding with a northern cold front, the report said, citing meteorologists.

An official in Xinmin township told AFP older houses suffered "very serious" damage including collapses, while newly built brick homes also were damaged.

"We're still gathering information about the disaster," the official said.

According to the People's Daily, the ruling Communist Party's mouthpiece, as many as 1,000 homes in six towns in Chongqing had at least partially collapsed in the storm, while thousands of others were damaged.

Power was cut in several areas, many roads in the region were blocked by flooding, and bridges also suffered damage, the report said.

The cost of the damage in the six towns was expected to surpass 20 million yuan (almost three million dollars), it added, citing preliminary estimates.

Chongqing, a province-sized municipality, has a population of more than 30 million people.

In Guizhou, five died in rain-triggered landslides while four were killed in Hunan, the state-run Xinhua news agency reported.

The toll rose to 39 after a missing person in Guizhou was confirmed dead.