HARBIN, July 21 -- Rescuers are working all-out to locate at least 12 miners trapped in a flooded coal mine in northeast China's Heilongjiang Province, local authorities said on Tuesday.

The flood inundated a colliery in Xing'an District of Hegang City, a major Chinese coal producer, at around 5 p.m. on Monday, the city government's publicity department told Xinhua.

Earlier reports said 12 miners were trapped, but several sources confirmed to Xinhua the number of stranded workers was more than that.

The emergency rescue headquarters said they were unable to confirm the exact number.

It said two rescue schemes had been worked out. The first involves drilling into the shaft and piping in oxygen and food through the hole, the second excavating into a separate shaft for rescuers to gradually approach the flooded area.

Dozens of electricians have been posted to the site with dynamos to support the rescue operation.