Two teenagers and a 20-year-old man have been arrested and charged with murder in connection with a shooting that killed four young people at a Sweet Sixteen birthday party, investigators in Alabama said.

District attorney Mike Segrest said the pair – Ty Reik McCullough, 17, and Travis McCullough, 16, both of Tuskegee – would be tried as adults.

That is automatically required in Alabama for anyone 16 or older charged with murder.

Investigators said that Wilson LaMar Hill Jr, 20, of Auburn was arrested on the same charge.

A makeshift memorial was created at the scene of the fatal shooting (Mickey Welsh/The Montgomery Advertiser via AP)

Mr Segrest said prosecutors would ask a judge to hold them without bail.

A bail hearing must be held by Friday under Alabama law.

Online court records do not show any previous adult charges in state court for either of the arrested teenagers.

Saturday’s violence shocked Dadeville, a sleepy town of 3,200 about 45 minutes from Tuskegee.

The birthday girl’s brother, Philstavious “Phil” Dowdell, died in his sister’s arms.

He and another victim, Shaunkivia Nicole “KeKe” Smith, were high school seniors, and families were left planning funerals instead of graduation celebrations.

Two young men were also killed.

Another 32 people were wounded and Mr Segrest said four are still in a critical condition.

He said more charges would be coming.

“We’re going to make sure all those victims have justice, not just the deceased,” Mr Segrest said, speaking to reporters in front of the town courthouse.

Shaunkivia Nicole Smith, was one of four people killed (Family/PA)

The gunfire broke out at a birthday party for Alexis Dowdell at a dance studio just off the town’s courthouse square.

Witnesses had said multiple people began shooting some time after Alexis’s mother paused the celebration to ask people with guns to leave.

A family member of KeKe Smith said she was thankful for the arrests.

“It don’t make the hurt any easier. But we are relieved that they (the suspects) are not out in the community,” Amy Jackson said.

Sergeant Jeremy J Burkett of the Alabama Law Enforcement Agency would not say where the two suspects are being jailed, or whether they were already in custody when they were charged in the case.

“We can’t get into a motive right now, because that would be part of an ongoing investigation,” Sgt Burkett added.

“We can’t share that.”

Those killed were: Phil Dowdell, a star wide receiver with plans to play college football; KeKe Smith, 17, an athlete-turned-team manager; Marsiah Emmanuel “Siah” Collins, 19, an aspiring singer and 2022 Opelika High School graduate who planned to start college this autumn; and 2018 Dadeville High graduate Corbin Dahmontrey Holston, 23, another former athlete at the school.

Mr Holston had gone to the party to check on a younger family member who feared trouble, his mother Janett Heard told AL.com.

Relatives told the news outlet that the shooting began shortly after Mr Holston arrived, and that he pulled his younger relative to safety.

In 2020, Alabama had the fifth highest rate of gun deaths in the country, according to the US Centres for Disease Control and Prevention.