Six workers were rescued from a flooded coal mine in Heilongjiang province on Monday morning, local authorities said.

The six were brought to the ground at about 5:30 am, according to the emergency rescue headquarters at Xuxiang Colliery in Hegang.

Four miners died, and rescuers raced to reach five other workers who had been trapped in the mine for about seven days.

The six rescued workers were in stable condition and had no obvious injuries, said Wang Falun, vice-president of Hegang People's Hospital.

However, Wang said, there were problems with their feet, which had been submerged in cold water for days, and it would take four to five days to recover.

Some time would also be needed before the rescued workers could eat normally again, because they had not eaten for days while they were underground, Wang said.

"When we first saw them, they were still nervous, but after being assessed by psychologists they gradually calmed down," he said.

Water inundated the mine at about 5 pm on July 20, trapping 15 miners. Investigators said the flooding was caused by a rainstorm.

Hegang is a major coal producer, and the privately owned Xuxiang Coal Mine has an annual output of 150,000 metric tons.