In a Facebook post on Friday, the state Game Commission said the mature bird was found near the Hope Cemetery in Elk Creek Township, about 20 miles southwest of Erie. The commission is asking the public for help in catching the gunman.
The incident is the second involving a bald eagle this month.
Authorities in Long Island, N.Y., are offering a $20,000 reward for the return of a bald eagle that was kidnapped July 16 from a wildlife refuge.
Surveillance footage appears to show someone arriving at the refuge in the early morning hours and leaving with a "satchel or bag" in his hand.
Earlier this year, seven bald eagles were fatally poisoned in Maryland. Officials believe their deaths were collateral damage from an attempt to poison so-called "nuisance animals" like raccoons and foxes. Three years ago, in 2016, 13 bald eagles were found dead at a Maryland farm.
The iconic American bird was on the federal endangered species list for several decades but was removed in 2007 as its numbers increased. However, the 1940 Bald and Golden Eagle Protection Act makes it a federal crime to kill a bald eagle.