At least nine workers are trapped inside a flooded coal mine in India’s northeastern Assam state, officials said Tuesday, as authorities summoned the army to help in the rescue operation.

The miners became trapped on Monday morning in the Umrangso area in Dima Hasao district, about 125 miles (200 kilometers) south of the state capital, Guwahati.

The workers are “feared trapped 300 feet below the ground after water gushed in from a nearby unused mine. We are mobilizing resources to rescue them,” said Kaushik Rai, a local government minister who is monitoring the rescue efforts.

Army soldiers and a national disaster management team at the site used ropes and cranes to assist the ongoing operation.

This image provided by the Indian Army shows an aerial view of the site where at least nine workers are trapped inside a coal mine, in the Umrangso area of Dimapur Hasao district in the northeastern state of Assam, India, on Tuesday, Jan. 7, 2025.  (Indian Army via AP)

Rescuers found three helmets, some slippers and a few other items, Rai said. “The divers have been able to dive into 35 or 40 feet of water inside the mine. The water level now is estimated at 100 feet,” he said.

Assam Chief Minister Himanta Biswa Sarma said on the social media platform X that the mine appeared to be illegal and that police had arrested one person as they investigate the case.

Workers at the site said over a dozen miners had been trapped inside the mine, which has minimum safety measures, and some managed to escape as water from a nearby unused mine began filling the mine.

In India’s east and northeast, workers extract coal in hazardous conditions in small “rat hole” mines that are narrow pits in the ground, usually meant for one person to go down, and are common in hilly areas. The coal is usually placed in boxes that are hoisted to the surface with pulleys. In some cases, miners carry coal in baskets up on wooden slats flanking the walls of the mines.

Accidents in illegal mines are frequent and the livelihoods of those who do such mining depend on the illegal sale of coal. At least 15 miners were killed after getting trapped in one such mine in Meghalaya state in 2019.