GREENDALE, Wis. —  A 91-year-old woman who had crawled under her car to look for her keys ended up stuck beneath an axle for two days until her mail carrier noticed letters piling up, police said.

Betty Borowski, of the Milwaukee suburb of Greendale, was found Tuesday and remained in a hospital in critical intensive care Friday, her niece Nancy DiMarco said. The hospital would not give an update on her condition Saturday.

Borowski, who lives alone, became stuck June 29 while looking for her keys; her head apparently got pinned by the axle, Greendale Police Chief Rob Dams said.

"She was pretty well wedged in there," Dams said. "It looks like she crawled under headfirst."

Borowski's mail carrier noticed Tuesday that the previous day's mail was still in her mailbox, police said. He rang the doorbell and then asked a neighbor whether he had seen Borowski lately. He hadn't, so they called police.

Firefighters lifted the car with a jack and removed Borowski, who was dehydrated and confused.

It turned out her keys were in the car door.

Borowski appears to be recovering, DiMarco said, but may have suffered a minor heart attack while under the vehicle.

"If it wasn't for people seeing a situation and following through ... who knows?" she said. "She wouldn't have made it about one more day."