(CNN) -- Investigators want to know what's behind a gruesome discovery at an urban Detroit farm: five goats and seven chickens slain without explanation.
"It was a pretty gruesome scene," said Mark Ramos, senior investigator for the Michigan Humane Society. "I can't comment on much more because it's still an open investigation, but it was pretty gruesome."
The farm, which sits in the middle of Detroit, is attached to Catherine Ferguson Academy, an alternative school that provides high school education to pregnant teens.
The fenced-in school campus consists of a large school building, which takes up two city blocks, several art buildings and a couple of barns. The animals were kept in a pen at the rear of the school.
A school official found goats and chickens slaughtered Friday morning and contacted Detroit police. The Michigan Humane Society then took over the investigation. Two other chickens were found injured and were removed from the scene.
The motive or weapons used in the attack were not immediately known, Ramos said.
The investigation will determine if any criminal charges will follow, he said.
The Humane Society cleared the dead animals and evidence from the scene Friday.
Attempts to reach administrators at Catherine Ferguson Academy were not successful.
CNN's Laura Ly contributed to this report.