CHENGDU, April 28 -- Seven workers were killed and one person is missing after a gas explosion in a coal mine in southwest China's Sichuan Province on Monday afternoon, local authorities said on Tuesday.

The mine in Fulu Town, Leshan City, was undergoing a safety overhaul when the blast occurred at 1:30 p.m., according to the Leshan government's publicity department.

Three injured workers have been sent to hospital, as rescue work continues.

Six people, including the mine's owner, have been detained by police, according to the city government.

The licensed mine had an annual capacity of 90,000 tonnes, it said.