A Sarpy County Sheriff's Captain says it ended up being a vehicle backfiring, but law enforcement took no chances on a school day in Gretna.
They locked down Gretna High School and nearby Thomas Elementary around 8 a. m. until they determined there were no gunshots being fired in the area southeast of 204th St. and Nebraska Highway 370.
The all clear was eventually sounded after an investigation.
(Image courtesy of Sarpy County Sheriff)