Gunman believed to have gripe with Marines

WASHINGTON — A gunman who fired shots at a Washington-area Marine Corps museum and who is believed to be responsible for three similar incidents may have a grievance against the Corps, the FBI said yesterday.

John Perren, the acting assistant director for the FBI’s Washington field office, said investigators believe the person takes issue with the institution of the Marines, but not those in uniform. Authorities do not believe he wants to harm citizens or Marines, Perren said.

“We’d like to know what this grievance is and what we can do to try to help solve it,’’ he said.