A man was injured and his wife killed when a cannon was fired into a mobile home in San Diego's East County.

Richard Fox, 39, is charged with firing the cannon that killed his 38-year-old girlfriend, Jeanette Ogara. He will be arraigned Thursday.

Deputies said Fox called 911 early Tuesday to report his wife may have been killed with a homemade cannon by accident.

Emergency crews arrived around 12:30 a.m. to the location on Potrero Valley Road in a rural section of San Diego near the U.S.-Mexico border.

Fox and another man had been working on the cannon outside the home in the Twin Lakes Resort mobile home park when it fired, sending a projectile into the home officials said.

Deputies said Fox loaded the cannon with powder from fireworks.

Shrapnel from the explosion went into the side of the trailer, killing Fox's girlfriend according to deputies.

When deputies and U.S. Border Patrol agents arrived, they found the unidentified woman dead from injuries she suffered after the projectile damaged the home.

One of the two men working on the cannon was taken to Sharp Memorial Hospital.

A four-year-old girl that was inside home was not injured and is being cared for by neighbors.

Deputies that responded to the scene were heavily armed with assault rifles in an area where trailers and mobile homes were accessible only by a dirt road.

Investigators were waiting for a search warrant to stay on the property in order to complete a more extensive search.

Sgt. David Martinez with the San Diego County Sheriff's Dept. said it's legal to own a cannon but is not necessarily legal to fire it.

No word if alcohol or drugs were involved.

Keep up to date on breaking news: Download our improved iPhone app, follow us on Twitter @nbcsandiego, fan us on Facebook, sign up for our breaking news e-mail alerts or text SDBREAKING to 622339 to receive text messages for local breaking news. (For more info, text HELP. To end, text STOP. Message and data rates may apply.)