CHENGDU, April 2 (Xinhua) -- A fire that killed 30 people and engulfed about 15 hectares of forest in southwest China's Sichuan Province was extinguished Tuesday, local authorities said.

More than 600 people are conducting a blanket survey of the affected area to ensure that fire does not restart, said Tang Yi, an official with the safety watchdog of Sichuan's Liangshan Yi Autonomous Prefecture.

As of 3 p.m. Tuesday, five helicopters poured about 65 tonnes of water on to the fire over 14 trips, Tang said.

Local authorities have dispatched more than 600 people to put out the blaze which broke out at around 6 p.m. Saturday at a remote spot in the mountains at an altitude of over 3,700 meters.

Thirty people, including 27 firefighters and three locals, lost their lives while fighting the fire. The first 23 bodies have been transported to a funeral home in the city of Xichang.

Xie Shi'en, an official with the local firefighting squad, attributed the casualties to an "explosive blaze," an outburst of flames caused by wind, combustibles and dry air.

"Among all scenarios in a fire, an explosive blaze is the most dangerous, and also very rarely seen," Xie said.

Wang Xin, a firefighter who survived the blast, said the fire came on so suddenly and rampantly that trees on the ridge were burned down within seconds.

"All of a sudden, we heard a huge explosive sound from the ridge and saw a wall of flame rocket up. It was as if someone triggered a huge flamethrower," Wang said.

"I have never seen anything like this during my 18 years of firefighting," said Long Sheng, another survivor.

The provincial government of Sichuan has established a team to investigate the cause of the fire as well as the firefighting and rescue efforts. The team will also consult with experts to understand the explosive blaze.