The suspects - Ty Reik McCullough (17) and 16-year-old Travis McCullough, both from Tuskegee, were arrested and charged with four counts of reckless murder, Sergeant Jeremy Burkett of the Alabama Law Enforcement Agency said during a news conference on Wednesday.
The shooting on Saturday took place at the Mahogany Masterpiece Dance Studio in Dadeville, a community of 3200 people about 80km northeast of Montgomery.
"Make no mistake. This is Alabama and when you pull out a gun and you start shooting people, we're going to put you in jail," Burkett said. "We're tired of going to mothers and having to tell them these kids aren't coming home."
Of the nine injured who were still hospitalised, five were in critical condition, Heidi Smith, a spokesperson for Lake Martin Community Hospital, said on Monday.
Three teenagers and a 23-year-old man were killed in the shooting. One was a high school football player who was among those attending his sister's birthday party.
The Montgomery Advertiser newspaper, quoting the victim's grandmother, identified the slain teenager as Phil Dowdell, whom she said was set to graduate in a matter of weeks and planned to attend Jacksonville State University on a football scholarship.
The other deceased victims were identified as Shaunkivia Smith (17), Marsiah Collins (19) and Corbin Holston, aged 23.
The shooting follows separate outbreaks of deadly gun violence in Tennessee and Kentucky that prompted local leaders to call for tighter gun control measures.
Mass shootings have become commonplace in the United States, with at least 165 so far in 2023, the most at this point in the year since at least 2016, according to the Gun Violence Archive.
The non-profit group defines a mass shooting as any in which four or more people are wounded or killed, not including the shooter.
