Rescuers are running out of time in the desperate effort to find two men buried beneath gravel and mud after a Friday landslide at a Mississippi gravel pit.

The two men were at the bottom of the pit at Green Brothers Gravel, one of them driving an excavator and the other a truck, when a wall of sand and slurry collapsed on top of them around noon, The Clarion-Ledger reported. Additional slides and rain have intermittently halted recovery efforts. The men are believed to be trapped under about 12 feet of sludge.

A crane had been brought in to try to lift the excavator out of the slide, but failed. Officials were examining other avenues to possibly save the men on Monday morning, the fourth day of the search-and-rescue operation, WLBT reported.

Though authorities have not publicly identified the men, relatives told The Ledger those missing were Emmitt Shorter, 24, and James “Dee” Hemphill.

“It's a miracle if we find anyone alive,” Copiah County Sheriff Harold Jones told The Ledger. “I always have hope.”

The Mining Safety and Health Administration is taking the lead in the rescue operation, but other agencies, including the Mississippi Emergency Management Agency, were lending a hand.

“Additional equipment is coming in and we're going to continue going,” MEMA's Ray Coleman said during a Sunday news conference. “There's no stopping.”

About 25 men typically work at the Green Brothers Gravel site, an MSHA statement said.

Crystal Springs, where the mine is located, sits about 26 miles south of Jackson.