Video shows explosion at gender reveal party that ignited massive wildfire in Arizona last year

Video released by the U.S. Forest Service on Monday shows how an explosion at a gender reveal party caused a devastating wildfire in Arizona last year.

The footage, obtained by the Arizona Daily Star and other media outlets, shows the massive Sawmill Fire starting in the Santa Rita Mountain foothills on April 23, 2017.

The words "boy" and "girl" can be seen on the target before it explodes. Authorities say off-duty Border Patrol agent Dennis Dickey fired a rifle filled with Tannerite, a highly explosive substance, at the target as part of the gender reveal for his pregnant wife's baby.

"Start packing up! Start packing up!" a voice is heard saying in the video after the explosion.

The video was recorded by someone else who was at the scene.

The wildfire would spread over 47,000 acres of land and cost more than $8 million in damage. About 800 firefighters battled the huge blaze.

Dickey, who immediately reported the fire, admitted in court "it was a complete accident," according to the Arizona Daily Star.

He pleaded guilty to a misdemeanor in September and was sentenced to five years of probation. In addition, Dickey has to pay $8 million in damages.