A Pennsylvania woman may have fallen into a 30-foot sinkhole. Searchers don’t expect to find her alive.

A 64-year-old grandmother is believed to have fallen into a 30-foot sinkhole in Western Pennsylvania, and a state police spokesperson said Wednesday that after two days of searching, officials were not expecting to find her alive.

Elizabeth Pollard of Westmoreland County had been missing since Monday evening, according to her family. When police found Pollard’s car, they discovered a sinkhole, possibly newly formed, that was associated with an abandoned mine.

A large-scale search for Pollard, which included the local fire department and the state Department of Environmental Protection, was continuing Wednesday night.

Here’s what we know so far.

Pollard, 64, is a wife, mother, aunt, and grandmother living in the Unity Township community of Marguerite, about 40 miles east of Pittsburgh.

Public records show she has lived in Westmoreland County for at least 40 years. She previously worked at a local Walmart.

Pollard went looking for her cat, Pepper, Monday evening. She took her 5-year-old granddaughter with her in her car.

The family called the police around 1 a.m. Tuesday. About 3 a.m., Pennsylvania State Police found Pollard’s car parked behind a restaurant with her granddaughter safe inside.

Trooper Steve Limani, a state police spokesperson, said the young girl “nodded off in the car and woke up.” She told police that Pollard was looking for her cat. Pepper’s whereabouts are also unknown. The girl remained in the car until troopers found her.

Authorities located a sinkhole in the area they believe Pollard may have fallen. A camera lowered into the hole showed what could be a shoe about 30 feet below the surface, Limani said. But rescue crews said a listening device detected nothing.

“It almost feels like it opened up with her standing on top of it,” Limani said.

A sinkhole is an area of ground lacking natural external surface drainage. It can form when the ground below the surface can no longer support the land above, according to the U.S. Geological Survey.

The land usually stays intact for a period of time until the underground spaces just get too big. If there is not enough support for the land above the spaces, then a sudden, dramatic collapse of the land surface can happen.

In this case, the manhole-size opening had not been seen by hunters and restaurant workers who were in the area in the hours before Pollard’s disappearance, leading rescuers to speculate the sinkhole was new.

Sinkholes are most common in what geologists call karst terrain, which involves types of rock, including limestone, below the land surface that can naturally be dissolved by groundwater circulating through them. They can also happen due to old underground mines.

The most damage from sinkholes in the United States tends to occur in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee, and Pennsylvania. Florida, for example, is highly susceptible to sinkholes because it sits above limestone.

Police said sinkholes aren’t uncommon in Pollard’s Unity Township area, citing subsidence from coal mining activity in the region.

A team from the Pennsylvania Department of Environmental Protection, which responded to the scene, concluded the underground void was likely the result of work in the Marguerite Mine, last operated by the H.C. Frick Coke Co. in 1952. The Pittsburgh coal seam — the layer of visible coal that can be mined — is about 20 feet below the surface in that area.

DEP spokesperson Neil Shader said the state’s Bureau of Abandoned Mine Reclamation will examine the scene after the search is over.

Rescue crews had searched through the night Tuesday for Pollard.

Authorities used an excavator to dig in the area, where temperatures dropped below freezing overnight.

Rescuers had been using water to break down clay and dirt to remove it, but that action was making conditions dangerous “for potential other mine subsidence to take place,” said Limani.

Authorities said in a noon update Wednesday that the roof of the mine has collapsed in several places and is not stable. The sinkhole is in the village of Marguerite, about 40 miles east of Pittsburgh.

“The integrity of that mine is starting to become compromised,” Limani said.

While speaking with the local ABC affiliate, Pollard’s niece, Tabitha Pollard, shared a message on behalf of Elizabeth Pollard’s husband, Kenneth Pollard.

“My uncle just wants to say thanks for everybody’s prayers and continue prayers as we’re going through this hard time,” she said. “We appreciate everybody’s support in this time. Right now, all we’re really doing is hoping for the best.”

In an interview with CBS News, Pollard’s son, Axel Hayes, said he was experiencing a mix of emotions.

“I’m upset that she hasn’t been found yet, and I’m really just worried about whether she’s still down there, where she is down there, or she went somewhere and found somewhere safer,” Hayes said. “Right now, I just hope she’s alive and well, that she’s going to make it, that my niece still has a grandmother, that I still have a mother that I can talk to.”

This article contains information from the Associated Press.