Savannah Guthrie's mother, Nancy Guthrie, missing in Arizona

The mother of "Today" show host Savannah Guthrie is missing in Arizona.

Pima County Sheriff Chris Nanos told reporters Sunday evening that a family member called 911 around noon on Sunday to report that 84-year-old Nancy Guthrie was missing.

"We're here on a search and rescue mission, we hope," Nanos said.

Savannah Guthrie issued a statement on her mother's disappearance Monday, the "Today" show reported.

"On behalf of our family, I want to thank everyone for the thoughts, prayers and messages of support," she said. "Right now, our focus remains on the safe return of our dear mom."

Guthrie urged anyone with information to contact the Pima County Sheriff's Department.

CBS Phoenix affiliate KPHO-TV reports that Nanos said Nancy Guthrie was last seen at her home in the Catalina Foothills area at 9:30 p.m. Saturday.

His department issued a missing person poster:

According to KPHO-TV, Nanos said there were "concerning circumstances" found at the home and that homicide detectives are also investigating.

He added that she's "not in good physical health" and that there's "grave concern" about her.

Nanos wouldn't rule out foul play but said the search and rescue mission is being conducted by air and on the ground.