The shooting happened at a block party on July 2. Police said 30 people were shot. Two of the victims, an 18-year-old and a 20-year-old, died. Those wounded range in age from 13 to 32.
Detectives said they followed up on a lead in the case and executed a search warrant at the 17-year-old's home Friday morning.
He was arrested and initially charged with being a minor in possession of a firearm, possessing an assault weapon and reckless endangerment.
The July 2 shooting was the worst mass shooting in Baltimore since the riots of the Civil War.
"This was the reckless, cowardly act that happened here and that has permanently altered many lives and cost two people their lives," Baltimore Mayor Brandon Scott said following the shooting.
Police said on Friday that three of the victims remain in the hospital. They are listed in fair condition.
Investigators believe more people were likely involved in the shooting. There is a reward of up to $28,000 for any information that leads to an arrest and charges. Tipsters who would like to remain anonymous can provide information on the Metro Crime Stoppers of Maryland website.
