The body of a mummified elderly woman was discovered on Saturday in a trash-filled San Francisco house occupied by a woman believed to be her daughter, authorities told CBS SF.

Police believe the 90-year-old woman, not yet officially identified, was dead for five years before she was removed from the derelict home in the city's Inner Richmond neighborhood. Firefighters were forced to wear oxygen masks due to the amount of trash.

"The hoarding is reportedly so bad that it's up to the ceiling," District supervisor Eric Mar told the station.

The discovery came after the woman's alleged 65-year-old daughter recently told a tax consultant she was living with a body. The consultant alerted police.   

The body, found wrapped in a blanket, was turned over to the medical examiner's office to determine when and how she died. It's not clear why her daughter allegedly lived with her mother's corpse for five years surrounded by garbage, creating a buildup of hazardous pests.

"Public health was dealing with the rats, and reported spiders, black widows and other things," Mar told CBS SF. A professional cleaning crew was called in to deal with the hoard.

Neighbors say the 65-year-old kept a mysterious profile and shunned attempts at starting a conversation. When asked about her mom, she reportedly acted like things were fine although no one saw the mother in a while.

"I'm saddened that she couldn't let her mother go," Sharon Scott Kish, the woman's friend and neighbor, told the station.

"I saw her three days ago and I asked her, "Is your mother still with us?' And she said 'Yes.' Delusional. She was with her. She was, she was still with her."

The daughter is now receiving treatment at a local hospital, Mar said.