PORTAGE, Mich. (WOOD) — Police are growing increasingly worried as they search for a mother of eight who has been missing since Saturday.

Police identified the missing woman as Heather Kelley, 35, of Portage. The Portage Department of Public Safety and the Kalamazoo Sheriff’s Department started investigating after she was reported missing on Sunday.

“Since that time both agencies have been working shoulder to shoulder, pretty much around the clock to bring this to a conclusion,” Portage Public Safety Director Nicholas Armold said.

“Any time somebody is reported missing and especially four or five days into it, when there’s no reasonable explanation as to why they’re not around, is concerning,” he said. “I’m not willing to jump to any kind of conclusions.”

Word about her disappearance was spreading on the Missing In Michigan Facebook page.

But police were providing few details.

“There’s a lot of detail we’re not going to be able to go into,” Sheriff Richard Fuller said.

They confirmed that they recovered her vehicle, though they wouldn’t say where and wouldn’t say if it held any clues about her whereabouts.

“You go back to sometimes you can explain things and other times you can’t,” Armold said. “Right now we can’t exactly explain why we found her vehicle without her and we can’t find her, so yeah that’s concerning and that’s why we’ve put everything we have from both agencies onto this case.”

Kelley is described as 5’10”, 130 pounds with long blonde hair.

“Our real concern is to try to find this young lady for her family,” Armold said. “We know that they’re struggling with her being missing and it makes total sense.  Hopefully we can bring this to a happy conclusion at some point. We just need more time.”

Anyone with information is asked to call the Kalamazoo County Sheriff’s Department at 269.383.8821 or Portage Public Safety at 269.329.4567.