Four people were treated for minor injuries Wednesday and employees of several businesses were evacuated after a Garden City HAZMAT incident.

It started shortly before 11 a.m. in the 100 block of 34th Street

Crews from the Garden City Fire Department, Boise Fire Department, Boise Police Department, a bomb squad and a HAZMAT team were all called to the scene.

Four people were treated for minor injuries, following an explosion that was caused by a military artillery simulator round found in an alley. The training device was determined to be for a M21 Tank main gun.

"All it's designed to do is make a loud boom and a lot of light and that's exactly how they described," Garden Ctiy Police Sgt. Tyler Domeny said.

The device also released a powdery substance.

"The powder that was dispersed out of it is common with that as well; it's part of their training round as well," Domeny said.

Police blocked off 34th and 35th Streets between Brown Street and Chinden Blvd. as a precaution.

Streets and businesses in the area were reopened around 3:00 p.m.

Authorities believe the explosion was unintentional and there is no threat to the public.

An investigation on how the device ended up in the area is ongoing.

Police warned anyone who finds any similar device not to touch it and to report it to the nearest law enforcement agency.