Terrance Hough Jr., a 35-year-old off-duty firefighter, was arrested in connection with the shootings, police spokesman Lt. Thomas Stacho said.
No charges had been filed Thursday morning because police were still gathering evidence and interviewing witnesses, Stacho said. There was no phone listing for Hough's address.
Police had received a number of complaints in recent years about loud parties, fireworks and drag racing connected to the house where the victims were shot, Stacho said. Some complaint calls came from Hough's address, but no one called police about the party Thursday night.
The neighbors were throwing a party when two men and a woman, all in their 20s, were shot to death shortly after midnight, Stacho said. He said another man was shot in the elbow and a woman was wounded in the hand.
A police officer who lives nearby heard the shooting and arrested Hough, Stacho said. CBS station WOIO-TV reports that a search of Hough's home turned up 12 guns – seven handguns and five rifles.
"I came out of my house, looked over here and I seen the three kids lying there," said neighbor Al Thomas. "Some girl was crying and screaming, 'They killed my friend, my friend."
The area of neat ranch homes overlooking the industrial Cuyahoga River valley is popular among firefighters and police officers who are required to live in the city.
In another incident near Seattle, a man was shot during an argument at a fireworks celebration and later died. Fire officials said the scene was so hostile and unsafe when they arrived that they had to transport the victim to another location to continue treating him, reports CBS station KIRO-TV.
More than 100 people were present when the two men began arguing around 11:30 p.m. Wednesday in a parking lot in Skyway, an unincorporated area between Seattle and Renton, Wash. Paramedics called after the shooting found the crowd so threatening that they had to quickly take the wounded man out to continue CPR, said David Nelson, a spokesman for county Fire District 20.
The victim was identified only as a man in his thirties.
Sheriff's Detective Bob L. Conner said it was unclear whether moving the man before continuing CPR was a factor in his death. King County sheriff's deputies were searching for the suspect.