ZAOZHUANG, Shandong - The condition of 28 miners who were trapped underground at a coal mine in East China after a fire late on Wednesday remains unknown, say local authorities.

Rescuers had put the fire out by Thursday afternoon and lowered the temperature underground to about 40 C following the accident at the Fangbei Coal Mine in Zaozhuang city, Shandong province.

Rescue workers take a lift on Thursday down a mineshaft to continue their efforts to reach 28 miners who were trapped after a fire broke out underground on Wednesday in Zaozhuang, Shandong province. [Photo/Xinhua]

The mineshaft spewed plumes of yellowish smoke after an air compressor that was about 250 meters below the surface burst into flames on Wednesday afternoon, triggering the fire that caused the shaft to collapse.

The smoke had stopped by Thursday afternoon.

Related readings: Rescue continues for trapped miners Awards offered for rescue of miners Anxious wait for families, friends of trapped miners

A total of 91 miners had been working underground at the time the fire started. It trapped 28 of them but the rest managed to escape immediately after the fire broke out.

The authorities said late on Thursday that more than 1,000 rescuers had been sent to the mine where they were laying water hoses and struggling to dig through to where the trapped miners were believed to be.

The rescuers said the temperature will fall further in the shaft but noted that they had not managed to establish a line of communications to the trapped miners. Firefighters remained on stand-by in case additional fires broke out.

Residents from nearby villages gathered on Thursday afternoon outside the mine to await information about their loved ones.

"My nephew worked the late day shift yesterday and he didn't come back home last night," said a villager in his late 60s who gave his last name as Yang.

"So far, we know nothing about how he is."

Safety officials and experts led by Luo Lin, the head of the State Administration of Work Safety, arrived early on Thursday to oversee rescue work. Senior local officials, including Jiang Yikang, secretary of the Shandong provincial committee of the Communist Party of China, were also on the scene.

The mine is close to Taozhuang town, which has been well known for its coal mining for more than 300 years.

The colliery, which is owned by the Shandong Antai Coal Industry Company, started production in October 2010 after it was rebuilt to double its capacity to 150,000 tons a year.

In another incident, four people were killed and another was seriously injured on Thursday when a gas explosion ripped through a mine in Northwest China's Xinjiang Uygur autonomous region, Xinhua News Agency reported.

The incident happened at 10:50 am in a shaft at the Xinyuan Coal Mine, which is located in Barkol Kazak autonomous county. Twelve workers were in the shaft at the time, according to a spokesman from the region's coal safety supervision bureau.

Rescuers managed to pull the seven uninjured workers out of the shaft and sent the seriously injured miner to hospital for treatment.