Federal officials are investigating the death of 13 bald eagles.

The Baltimore Sun reports that investigators were called to a farm in Federalsburg on Saturday afternoon after a man discovered some of the birds.

Maryland Natural Resources Police spokeswoman Candy Thomson says the man was looking for shed deer antlers when he noticed four dead bald eagles. Thomson says officers went on to search the grounds and discovered an additional nine dead eagles.

The U.S. Fish and Wildlife Service is investigating.

Officials have not said whether the eagles were killed intentionally.