The only clue to Sherry Arnold's disappearance is a running shoe  the Montana school teacher left behind near one of her regular jogging routes.

But police and more than 300 people from Sidney, Montana are hoping to get more information about why Arnold went missing after a routine run Saturday morning.

It kind of makes you sick to your stomach that somebody was out jogging, minding their own business, and something or somebody or whoever had to do this to an innocent person. It's just not right, Bryan Prevost, a pilot who is using his private plane to help in the search, told local KULR-TV. And a small town like this, it just (doesn't) happen. And so everybody's really pulling together, and they're trying to make the best of a bad situation.

Arnold, a 43-year-old math teacher at Sidney High School for 18 years, was last seen at her home 6:30 a.m. on Jan 7. Search teams are using Montana Army National guards, canine units a helicopter and several airplanes, The Associated Press reported.

Assistant Police Chief bob Burnison told the AP that Arnold's disappearance is hard for the small 5,000-person town, who recently lost 46-year-old firefighter Jody Ray Verhasselt in an avalanche on New Year's Eve.

According to a Facebook page dedicated to her search, she is described as 5'10 tall, 140 1bs. With black hair. She was last seen wearing a blue sweatshirt with a white stripe, and red nylong pants with black leggings. People with any knowledge of her disappearance are encouraged to called the Sidney Montana Police Department at (406) 433-2210.