By John Dodge

CHICAGO (CBS) — Most people know the feeling, walking in an area and getting the sense that something isn’t quite right.

There is no obvious immediate threat, but just an uneasy instinct. It doesn’t rise to the level of a 911 call, at least not yet.

Recent University of Missouri graduate Zach Beattie, along with a team of fellow classmates, developed an app called Safe Trek, which is available for both iOS and Android devices.

After users download the app, they create a safety profile.

When the user starts to feel unsafe, they hold down the safety button and the app uses GPS to locate the user and follow their route.

If the perceived threat passes, users release the button and have 10 seconds to enter a four-digit PIN.

“I use this app almost everyday,” said one user. “I’m a young girl who only gets home at 3 or 4 in the morning on most nights. I used to always call one of my friends and make them stay on the phone with me to make sure I was OK, but now I don’t have to worry about that.”

If they don’t enter the PIN, the app dials 911 along with the Safe Trek operations center, that will help the user and police respond.

It essentially works like a home security system for a mobile device.

Beattie says he hopes the app helps police pinpoint problem areas, using data from the app’s users.

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