There has been a breakthrough in search and rescue efforts for trapped miners in a coal mine in southwest China's Sichuan Province, as rescuers started a new round of operation on Tuesday.

A total of 18 miners were trapped after the Shanmushu Coal Mine located in Yibin city was severely flooded on Saturday afternoon. Five of them have been confirmed dead, while another 13 remain missing.

At around 1 p.m. local time, a number of rescuers were sent underground. Together with them were some medical practitioners, who brought medication, stretchers and oxygen bags. Some 10 ambulances were on standby to provide immediate medical service to the miners once they were rescued.

The sudden action was considered as a sign that the miners have been found. But it has not been confirmed by either the mine operation company or local government. And it also remains unclear if there is any sign of life there.

On Tuesday morning, the rescue headquarters said that the elevation of the water level in the area where the workers are trapped has declined to about 124 meters. This is a big progress for the rescue work, which means that rescuers can carry out the next-phase operation, as the elevation of 128 meters is a threshold for further actions.

During the past few days, the rescuers have used different kinds of submersible pumps to discharge the flood water.

The cause of the accident still remains unclear. China's Emergency Management Ministry has ordered local authorities to announce the cause as soon as possible and hold related people accountable.

This is not the first time such an accident has happened in this mine. Back in 2013, seven workers were killed during a gas explosion.

In April this year, the mine company was investigated after it was found operating with excessively high gas concentration, putting 26 miners in an extremely dangerous situation.

These have shown loopholes in the management of the mine, raising a red flag for coal mines and workers across the country.