The police in Baltimore arrested an 18-year-old on Thursday evening in connection with a mass shooting during a block party in early July that killed two young people and left 28 others wounded, officials said.
The suspect, Tristan Brian Jackson, was charged with seven counts of attempted first-degree murder and seven counts of conspiracy to commit first-degree murder and 41 other related charges, the police said.
“While this arrest cannot undo the damage and trauma caused that day, it is my hope that it can bring some peace and justice to the families of all the victims and the Baltimore community,” Col. Richard Worley, the city’s acting police commissioner, said in a statement on Thursday.
It was not immediately clear if Mr. Jackson had an attorney.
In the early morning of July 2 in the neighborhood of Brooklyn in southern Baltimore, a barrage of gunfire tore through the Brooklyn Day block party, which officials described as an unauthorized event that had drawn hundreds. Bullets struck dozens of young people: Half of those shot were younger than 18, the police said.
In total, the victims ranged from 13 to 32 years old, Colonel Worley said at a news conference later that afternoon.
Officials said an 18-year-old woman, Aaliyah Gonzalez, had died at the scene of the shooting, which happened at the Brooklyn Homes, a public housing complex. A 20-year-old man, Kylis Fagbemi, was later pronounced dead at a hospital, the police said.
At the news conference in July, the city’s mayor, Brandon Scott, called the shooting a “reckless, cowardly act.” He said the shooting highlighted the need to address access to illegal guns and other factors that contribute to gun violence, and he criticized adults who did not intervene.
The shooting, footage of which surfaced online, spurred calls throughout the community for accountability. Mr. Scott urged those who witness dangerous behavior to contact the authorities instead of posting videos online.
Mr. Jackson is the second person charged in connection with the shooting. In July, a 17-year-old boy was charged with possession of a firearm by a minor, possession of an assault weapon, reckless endangerment and having a handgun in a vehicle.
The police have not said whether Mr. Jackson or the unidentified 17-year-old fired a weapon that fatally struck Ms. Gonzalez or Mr. Fagbemi. The authorities have said that there was more than one assailant but declined to provide more information, and a motive for the shooting remained unclear.
This year, there has been an increase in shootings involving children and teenagers in Baltimore, leading to an official city curfew for those 16 and younger.
In a statement on Thursday, Mr. Scott said, “While an arrest has been made, the investigation continues.”