A fire high in the mountains of western China’s Sichuan province has killed 30 firefighters and others, the government said Monday.

The deaths occurred after a change of wind Sunday as the firefighters were battling the blaze in a rugged area at an altitude of 3,800 meters (12,500 feet), according to the Ministry of Emergency Management and the military. Among the dead were 27 firefighters and three local residents recruited to help fight the blaze, the ministry said.

Nearly 700 people were battling the fire in Sichuan’s Muli county that erupted on Saturday, but contact was lost Sunday with the 30. Two helicopters carrying medical staff and military personnel were dispatched to help in the search.

In this photo released by Xinhua News Agency, a fire-fighting helicopter leaves on a mission to fight aforest fire in the Muli County in Liangshan Yi Autonomous Prefecture from an airport in Xichang, southwest China's Sichuan Province, Monday, April 1, 2019. (Lin Jiping/Xinhua via AP)
In this photo released by Xinhua News Agency, a fire-fighting helicopter leaves on a mission to fight aforest fire in the Muli County in Liangshan Yi Autonomous Prefecture from an airport in Xichang, southwest China’s Sichuan Province, Monday, April 1, 2019. (Lin Jiping/Xinhua via AP)

China has been battling forest fires in recent weeks in various parts of the vast country, including on the outskirts of Beijing, fed by dry weather and high winds across many northern areas.

The death toll among the firefighters appeared to be the worst since 2015, when an explosion at a chemical warehouse in the port city of Tianjin killed 173 people, most of them firefighters and other first responders. That blast was blamed on illegal construction and unsafe storage of volatile materials.

Scores of workers have also died in recent industrial accidents, including 85 in a pair of explosions last month.