Many residents in northern Arizona heard a series of large booms Saturday.
According to the Arizona Department of Emergency and Military Affairs, the engineering unit at Camp Navajo in Bellemont was conducting explosives training.
A spokesperson told KNAU that the exercises were necessary to familiarize soldiers with demolition equipment for rock blasting and grinding materials to create pavement and concrete for projects.
Some people in Flagstaff reported the shockwaves from the blasts shook their homes and windows.
The department had not announced training ahead of time. Officials say they realized the blasts were shocking to residents and they’ll post notices in advance of future projects.