Two teenage boys have been charged with murder after the shooting at a 16th birthday party in Alabama that killed four and injured 32 over the weekend.
Brothers Ty Reik McCullough, 17, and Travis McCullough, 16, were arrested on Tuesday night, police said.
Authorities said the suspects are each being charged with four counts of reckless murder and that more charges are expected.
Hours later, police announced the arrest of a third suspect.
Wilson LaMar Hill, 20, is facing the same charges as the two boys, who prosecutors say will be charged as adults.
At a press conference on Wednesday, officials told reporters that these were the early stages of the investigation into the shooting on Saturday in Dadeville and offered very details.
No information was given about a motive or the type of firearm used.
Police said that among the 32 people injured, four remain in hospital in a critical condition.
“We are going to make sure every one of those victims has justice and not just the deceased,” Sgt Jeremy Burkett of the Alabama Law Enforcement Agency (ALEA) said.
The agency added: “These individuals have been charged after a complex and thorough investigation was conducted with assistance from a multitude of law enforcement agencies.”
Until Wednesday, police had offered few details since the shooting on any suspects in the case.
District Attorney Mike Segrest said: “I know that there has been some frustration among our community and among media about a lack of information that has been provided up to this point.”
The deceased victims have been identified as Marsiah Collins, 19; Phil Dowdell, 18; Corbin Holston, 23; and Shaunkivia Smith, 17.
Mr Dowdell died trying to save his sister Alexis, his family has said. He was a star athlete on his high school’s American football team and had been due to graduate to go to Jacksonville State University on a sports scholarship.
One of his friends and school football teammate told the BBC: “Phil to me was an amazing friend. God’s got an angel.”
There were about 50 people at the party, which was held at a local dance studio.
Dadeville, a town of roughly 3,000 residents, is about 60 miles (100km) north east of the state capital of Montgomery.
Officials said the two teenage brothers who have been arrested are from Tuskegee, Alabama, which is about a 40-minute drive from Dadeville.
Sgt Burkett urged those who were at the party at the dance studio to contact authorities if they have not already done so.
“We need you to come forward for these families, for these victims,” he said.
The weekend attack took the US to a grim milestone of more than 160 mass shootings this year, according to the Gun Violence Archive, which defines such events as ones in which four or more people are shot.
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