LUZHOU - A coal mine gas explosion that killed 28 miners in southwest China's Sichuan Province was a result of illegal mining, officials said on Sunday.

An initial investigation indicated that unauthorized mining at the Taozigou coal mine was the main reason behind the gas blast.

The explosion was a result of high gas density due to poor ventilation, Fu Jianhua, deputy director of the State Administration of Work Safety (SAWS), told an emergency press conference in Luzhou, where the accident happened.

The administration supervises the country's mining activities.

A total of 108 miners were working underground when the blast happened around 2 p.m. on Saturday in the mine in Luxian County of Luzhou, sources with the provincial work safety bureau said.

As of Sunday afternoon, the blast had left 28 miners dead and 18 others injured, including eight in critical condition.

The injured were sent to a local hospital for treatment, with three remaining in life-threatening condition.

Liu Jie, deputy governor of Sichuan, said the Taozigou coal mine should be shut down "as soon as possible," and production at all coal mines in the province should be suspended for an overhaul.

SAWS director Yang Dongliang said all licenses of the coal mine must be revoked and the site will be shut down permanently.

Meanwhile, the number of casualties needs to be verified, and the injured should be treated, Yang said.

He added that a thorough investigation into the cause of the accident should be carried out so that those responsible are dealt with in accordance with the law.