Authorities in the Waco area are investigating a Facebook video showing a group of teenagers mutilating a dead dog for laughs.

The dog apparently died before the video was shot, the Waco Tribune-Herald reports, but it's what the young men did afterward that outraged animal lovers.

"The video is extremely disturbing," Hewitt Police Chief Jim Devlin said Saturday morning, "and even the little bit of information that was with the video prompted us to open an investigation."

The cellphone video shows one of the teens shooting the dog's corpse repeatedly in the head with a handgun, then zooming in on the resulting carnage.

Later the teens place a firecracker in the dog's body and blow it up. The video ends with a closeup of the dog's head on fire.