A cormorant, like the one pictured here, was among five birds shot in the Patapsco River. (Toni L. Sandys/The Washington Post)

A Maryland transportation officer and his two companions are being investigated after police said shots fired from a boat they were operating near the Key Bridge in Baltimore left several birds dead, and some ammunition may have passed near an evening dinner cruise ship.

Authorities said five birds, including a federally protected gull and a double-crested cormorant, were killed in the July 21 incident and more than 300 rounds of ammunition for several weapons were found in the boat.

A Baltimore police spokeswoman identified one of the suspects as an off-duty officer with the Maryland Transportation Authority, responsible for state bridges, toll roads, Baltimore-Washington International Marshall Airport and the Port of Baltimore. She did not release a name, because charges have not been filed.

Lt. Kevin Ayd, a spokesman for the Maryland Transportation Authority Police, said the officer’s police powers have been suspended and he has been put on administrative duty for the duration of the investigation.

Police said charges are pending, but authorities first need to determine which agency has jurisdiction. Federal authorities have a stake in the case because of the harm to the birds. Baltimore police also have interest because the boat was in the Patapsco River, about six miles from the Inner Harbor, before being chased into a nearby creek.

The incident began about 8:30 p.m., when Baltimore police said they received two emergency calls — one for people in a boat shooting at birds and a second for what appeared to shots fired in the direction of the Spirit of Baltimore, a cruise ship that offers daily excursions from Baltimore’s Inner Harbor.

Dan Leaman, the general manager for Entertainment Cruises, which runs the Spirit line, said no shots were fired near the ship, but he said the captain directed police toward the shooting. He said he does not believe patrons on the ship were aware of the gunfire.

Marine officers from the city and Maryland Natural Resources Police, along with the U.S. Coast Guard, raced in boats to the area and chased the green, 21-foot, center console boat at high speeds several miles to Bear Creek, near Dundalk, Md.

Nicole Monroe, a spokeswoman for Baltimore police, said an observer in the police helicopter Foxtrot saw one of the people in the boat throw a long gun into the water. The observer was able to photograph it and mark the location.

Authorities said the helicopter forced the boat to a stop, and police detained the three occupants. A long rifle was recovered from the water, police said.

Monroe said officers recovered 210 rounds of shotgun ammunition, 50 rounds of 9mm ammunition, 100 rounds of 5.7mm ammunition and 12 rounds of .22 caliber ammunition from the boat. She said that the speech of all three people on the boat was slurred and that there were empty beer cans in the boat. Each person was given field sobriety tests, she said; the results were not released pending charges.