Divers found two firearms, ammunition and a tear-gas grenade Monday morning during an underwater training exercise near the Port of Buffalo docks, the Coast Guard said.
Police sealed off part of the harbor as the day's events turned from training to real-life hazard.
The Erie County Sheriff's Department Bomb Squad recovered and then took possession of the tear-gas grenade, which could have exploded even underwater.
The guns were turned over to Buffalo police and will be traced to find out whether they had been involved in crimes.
It all started when volunteer firefighters in the Hamburg Water Rescue Unit noticed a package at the bottom of the lake during a training drill, said Chief Boatswain's Mate William Carter, who is in charge of the Coast Guard's Buffalo station.
"They just happened upon it while out there on a training dive," Carter said.
Officials would not describe the size or shape of the package or say what it is made of. The divers found the package beneath 20 feet of water and 15 yards from the shore.
It is unlikely a passing boat could have detonated the grenade.
Still, the tear-gas grenade was armed and posed a threat, Carter said.
One of the volunteer divers who chanced upon the package opened it using his knife. The diver left the package alone after discovering its contents, Carter said.
The Hamburg divers then summoned police to the scene. Buffalo police and agents from the Federal Bureau of Investigation and the Bureau of Alcohol, Tobacco and Firearms responded.
The guns were discovered in the Buffalo Harbor near the Euro United plant, at 701 Fuhrmann Blvd., in the former Tops distribution center.
The Coast Guard and Erie County Sheriff's Department took about an hour to recover the items, Carter said.
Tech. Sgt. Martin R. Wolinski of the Erie County Sheriff's Department Bomb Squad was called to the scene to retrieve the tear-gas grenade.
The Hamburg volunteers tied a string onto the package and connected it to a life jacket on the surface of the water. A boat later towed the package to shore.
"It appears to be operable," Wolinski said of the military-style grenade, which is about the size of a baseball and weighs a half-pound.
The grenade would have exploded had the diver pulled the pin from the device, he said.