Heavy machinery and sound-monitoring equipment are being used in the search for a Pennsylvania grandmother believed to have fallen through a sinkhole deep into fragile, unstable ground while searching Monday for her cat, authorities said.

Amid danger of a collapse, rescuers have been pumping water through a long-abandoned mine at the site to clear out debris, then remove it with a vacuum, to make it easier to see what is underground, Pennsylvania State Police said early Wednesday.

“The integrity of that mine is starting to become compromised,” Trooper Steve Limani said in a news conference.

Rescuers hope Elizabeth Pollard, 64, is still alive in an air pocket, officials have said, noting the hole has plenty of oxygen and is about 55 degrees, far warmer than above ground. And though shifting ground is slowing the search, state police will not stop until they have answers, they’ve said.

“There’s been nothing that said she is not alive or she could not possibly have survived. There’s nothing that said 100% definitively it couldn’t have happened,” Limani said. “And until that 100% happens, how could I say it’s any other way?”

64-year-old last seen behind restaurant

Police got a phone call around 1 a.m. Tuesday from a relative of Pollard who said the grandmother, with her 5-year-old granddaughter, had left in a car to look for her cat the prior afternoon and had not been heard from since, State Police said Tuesday.

Pollard was last seen around 5 p.m. Monday in Marguerite, an unincorporated area of Unity Township, Limani said, in a part of southwestern Pennsylvania dotted with old coal mines.

Police out looking for the woman discovered her vehicle – with her granddaughter inside – parked near a restaurant.

A fresh, deep sinkhole was just steps away.

“We, at that point in time, realized that this could be a very bad situation,” Limani said.

The granddaughter, who’d been in the car for nearly 12 hours in below-freezing temperatures, was unharmed, Limani said. But the girl, now with her parents, couldn’t give police any details about what happened.

“She was just a 5-year-old girl that was waiting in the car for her grandmother to come back,” he said.

No sounds picked up by monitors in search

The sinkhole, which was about 15 to 20 feet from Pollard’s vehicle, appears to be about the size of a manhole at the surface but gets much wider below ground, making search and rescue efforts challenging, Limani said.

The sinkhole likely appeared at some point Monday, officials said.

“That hole wasn’t there earlier in the day,” Limani said. “It’s close enough to the building that somebody would have seen it.”

While no sounds have been picked up by monitoring equipment, the rescue teams spotted a shoe in the sinkhole Tuesday using a camera, Pleasant Valley Volunteer Fire Company Chief John Bacha said.

“Let’s just say it’s a modern shoe, not something you would find in a coal mine in Marguerite in 1940,” he said.

Bacha took an initial look in the hole Tuesday using a ladder and a harness but did not spot Pollard, he said.

“You couldn’t even get close enough to the hole because of the way it was undermined,” Bacha said.

“A lot of the little villages around here are old coal patch towns,” he said. “(It’s) very common to find a lot of mines in these areas, obviously a concern to have these mine subsidence issues.”

“Let’s be honest,” Limani added, “we need to get a little bit lucky.”