Missing Pennsylvania grandmother believed to have fallen into 30-foot sinkhole

UNITY TWP., Pa. -- GET LATEST HERE: Rescuers continue search for woman who may have fallen into a sinkhole while looking for lost cat

A Pennsylvania grandmother who went missing while looking for her cat is believed to have fallen into a deep 30-foot sinkhole, authorities said.

A search and rescue mission is currently underway in Unity Township for Elizabeth Pollard, Pennsylvania State Police said Tuesday.

The sinkhole is believed to be tied to an abandoned coal mine, officials said.

Search crews have been able to make entry into the mine area but there have been no signs of Pollard yet, Trooper Steve Limani told reporters at the scene Tuesday evening. The search is expected to continue into the night, he said.

"Hopefully she's in an air pocket," Limani said, noting that there have been incidents in the region where people have survived similar situations in underground mines. "This is a rescue to me until something says that it's not."

The search will continue as long as needed pending any safety concerns, he said.

Rescue teams from nearby areas have joined forces, swapping shifts to keep the effort going. Oxygen tankers are being delivered regularly to supply the mine shaft, and crews have made progress entering the underground area.

The conditions are tough, with clay-like soil making it difficult to dig, but rescuers remain determined. "We're doing everything we can, and no one is giving up," said Liman

He added, "It's heartbreaking for her family and everyone here. But we're not stopping. We're all hoping for a miracle."

Pollard was reported missing by a family member shortly before 1 a.m. Tuesday, Limani said at an earlier press conference Tuesday.

Pollard was last seen around 5 p.m. Monday, Limani said. The family member said Pollard had gone out to look for her cat Monday afternoon but has not been heard from since, he said.

Pollard's vehicle was located shortly before 3 a.m. Tuesday with her 5-year-old granddaughter inside, though Pollard was nowhere to be seen, police said.

"At that point in time we realized this could be a very bad situation," Limani said.

While searching for Pollard in the area, troopers found an apparent sinkhole with an opening about the "size of a manhole" 15 to 20 feet away from the vehicle, Limani said.

Emergency responders were called to the scene in what is currently being considered a rescue mission, authorities said. Local firefighters, a technical rescue team and the state's Bureau of Mine Safety are among those working alongside an excavation team to remove dirt to access the sinkhole, Limani said.

The current evidence points toward Pollard being in the sinkhole, Limani said.

"We don't feel a reason that we should be looking elsewhere," he said.

The sinkhole appears to have been created during the time that Pollard was walking around, Limani said, noting that there is no evidence that the hole was there before she started looking for her cat.

A camera inserted into the opening of the sinkhole showed a "big void, and it was all different depths," Marguerite Fire Chief Scot Graham told reporters during the earlier press briefing.

"The process is long and it is tedious," Graham said.

A camera did not pick up any sounds, though authorities did see a "modern-type" shoe in the sinkhole, according to Pleasant Unity Fire Chief John Bacha.

The mine last operated in 1952, according to the state's Department of Environmental Protection. The depth to the coal seam in this area is approximately 20 feet, a department spokesperson said.

Once the scene is clear, the department will investigate the site "to determine if this issue is the result of historic mine subsidence," the spokesperson said.

Pollard's granddaughter is safe, despite the cold temperatures overnight, and is currently with her parents, Limani said.

The family is asking for privacy at this time and is hoping for "good news," he said.

"We need to get a little bit lucky," Limani said. "We're going to do everything we can."

ABC News' Alexandra Faul and Jason Volack contributed to this report.