Search and rescue operations are underway in Uttarakhand, a state in northern India, in a race to rescue nearly 150 people still missing after a massive flood caused by a glacial avalanche left at least 26 dead Sunday.
A piece of a Himalayan glacier broke off and fell into the Dhauliganga River, triggering flood waters and falling rocks that broke open a dam and sent a barrage of water rushing into the valley below, according to the BBC.
Videos from the scene show the glacier leaving clouds of debris and flattening the land in its wake.
Most of the 150 missing are reportedly believed to be workers from two hydroelectric projects in the surrounding area that were hit by the avalanche.
Uttarkhand's police chief told CNN Monday that among those missing are 35 workers believed to be trapped in a tunnel more than 600 feet long at a state-owned hydroelectric project.
The workers reportedly haven't made any contact since Sunday. Officials said it was difficult to deduce whether all the workers are still together and where specifically in the tunnel they may be located, the outlet said.
India's NDTV broadcaster reported that the entry to the 12-foot tall and 15-wide tunnel was blocked with debris and slush. Rescuers are currently focused on clearing debris from the tunnel's opening.
By Monday, rescuers had reached all 13 villages initially cut off by the floods, according to CNN, as relief work continues in the region.
Below, images show the devastation wrought by the glacial avalanche.