Durham, N.C. — The Homestead Market Shopping Center in Durham is back open Tuesday morning after police found a suspicious device outside one of the stores.

Authorities were originally called to the shopping center at around 3 a.m. to respond to a burglar alarm at "TCBY Yogurt," one of the businesses in the shopping center. While authorities were checking the area, they found a ladder propped up behind a Harris Teeter grocery store.

Investigators said a suspicious device shaped like a hand grenade was at the top of the ladder. A bomb squad was called in to investigate and discovered it was a training grenade.

Authorities said the training grenade did not have any kind of mechanism that would cause it to detonate. That type of grenade can be purchased at military surplus stores.

Officers are trying to determine who placed the training grenade on the ladder as well as a possible motive.

The shopping center was closed for nearly three hours while authorities conducted their investigation.