Two Florida teens are under investigation for repeatedly lighting an endangered gopher tortoise on fire, fatally stomping it to death as it cowered inside its shell, and then posting videos of the torture on Facebook.

A concerned classmate brought the videos to the attention of an animal rights group in Nevada, and they've since been forwarded to Florida's Fish and Wildlife Conservation Commission. The Florida Times-Union reports the State's Attorney's office is determining appropriate charges for the two Orange Park girls, ages 15 and 18.

The videos are no longer online, but First Coast news aired this clip of the girls pouring flammable chemicals on the tortoise and torching it with a lighter:

The Times-Union also obtained the footage from Nevada Voters for Animals, and their story describes some of the gruesome lowlights:

"Burn baby, burn baby," one girl says as they light the tortoise on fire. "Now you are scared of us, huh?" "He's — — hissing still," one says as they pick the struggling animal up. "Let's do it again," the videographer said. "Let me do it. He's not dead. He just went in his shell." "His heart came out with a bunch of grass," the girl with the camera says as she laughs, then kicks the corpse. "He's dead. That's funny."

"We received quite a few complaints about this and a call from the Sheriff's Office, so we had an officer go out last night," a Florida Fish and Wildlife officer told the paper, "Everybody is pretty much sickened by it and can't believe someone would do that to an innocent animal."

Although the girls haven't officially been arrested yet, they could be charged with aggravated animal cruelty, with additional felony charges because the gopher tortoise is on the state's threatened species list.

Meanwhile, internet vigilantes at 4chan have started their own investigation of the incident, the Daily Dot reports. They've doxed the girls and sent their names to their high school, local authorities, and news outlets in an effort they're calling "Operation Shell Shock" (of course).

When a Times-Union reporter went to one of the suspects' houses Wednesday, a girl who appeared to be one of the two in the video answered the door, but closed it without saying anything.

[H/T Daily Dot]