Three maintenance workers remain trapped inside a coal mine in east China's Jiangxi Province after a tunnel collapsed Saturday night, local authorities said Sunday.

The accident happened at about 7:20 p.m. at a coal mine in the township of Nanyi in Ruichang City, according to the rescue command headquarters.

The rescue effort was still under way as of 6:30 p.m. Sunday.

The coal mine was operating legally with all required credentials, according to the government of Ruichang.