At least 91 people, including 32 women, have gone missing after a massive landslide struck an industrial estate in China's Shenzen city, prompting government to step up rescue efforts in one of the country's worst urban disasters.

The 91 missing included 59 men and 32 women, state-run Xinhua news agency quoted officials as saying.

In what is being regarded as one of China's worst urban disasters, hundreds of tonnes of mud from a crumbling mountain engulfed 33 buildings and triggered an explosion at a gas station in an industrial park in Shenzhen yesterday.

More than 1,500 people, including firemen, police and health workers are involved in the rescue operations, searching the debris for trapped victims.

The rescue headquarters said they have detected signs of life at three separate locations of the site. Rescuers were battling unfavourable geological conditions to save those trapped under the debris.

"The site is quite narrow and is located on a ramp, so it is very difficult for vehicles to enter. We have to go there on foot," said Ao Zhuoqian, an official of Shenzhen's fire control department.

Rescue efforts were being hampered by a spate of obstacles, including rain, low nighttime visibility and the large amount of mud, Ao said.

The landslide buried 33 residential and industrial buildings, officials said.

A statement on Weibo, China's micro-blogging site akin to Twitter, from the Shenzhen municipal government said the landslide also triggered an explosion at a nearby gas station.

A nearby section of the West-to-East natural gas pipeline exploded after the landslide struck the Hengtaiyu industrial park at around 11:40 AM which resulted in amassing of more than 100,000 square metres of debris.

Videos on China's social media showed vast amounts of red mud pouring into the city



The mud slide slowed down as it approached the main area of the estate giving time for many people to escape.

Rescuers evacuated over 900 residents from the site by evening.

A resident living about 4 kms away from the site told Xinhua that he heard "a loud explosion" yesterday.

"It must be a big accident, as I could hear the sound from so far away," he said.

An employee with the Liuxu Technology Co in the park said power supply in the company suddenly went down around noon.

"I saw red earth and mud running towards the company building. Fortunately, our building was not hit, and all people in our company were safely evacuated," he said.

The mud has covered an area of more than 60,000 square meters with an average thickness of 6 meters, according to geological experts at the site.

Chinese President Xi Jinping and Premier Li Keqiang have ordered immediate rescue efforts and prevent secondary disasters.