Thirteen young miners were missing and feared dead following the collapse of a shaft and flooding of a coal mine they were digging illegally in India's remote northeast, police said Friday.

Rescuers were attempting to pump water out of the mine, which flooded Wednesday, police said. National Disaster Response Force workers joined local authorities in the rescue effort.

Police said rescuers can only reach the miners after the water is removed from the mine.

Those missing are believed to be teenage boys used by illegal mining groups to enter "rat hole'" mines with small openings.

They said digging at the mine was banned four years ago, but illegal and unsafe activity by private landowners and the local community is rife. The area in Meghalaya state is about 130 kilometers (80 miles) north of Shillong, the state capital.

"It was absolutely an illegal mining activity," said Conrad Sangma, the state's top elected official. He said authorities would crack down on illegal mining groups.

Last month, an activist, Agnes Kharshiing, was assaulted by people involved in illegal mining when she visited the area to protest their activities. She remains hospitalized with life-threatening head and other injuries.

Demand for coal has increased in energy-hungry India.

Migrants from poorer parts of the country come to work illegally in the coal mine area, where they earn enough money to pay off powerful people who make sure the mines' guards don't interfere. People carrying baskets filled with stolen coal on carts or bicycles are a common sight in these areas.

In 2016, six illegal miners died when a section of a closed mine collapsed in Burdwan district in India's West Bengal state. The accident occurred when about 200 illegal miners were extracting coal from the mine.