Local police in Middlesex county are investigating three shootings within a 12-hour period, which is “the most significant surge in gun violence” for the communities in years, according to officials.

The Middlesex DA’s Office is reporting that three shootings occurred across Cambridge, Somerville and Belmont from Monday afternoon to just after midnight on Tuesday.

In that third shooting after midnight, Somerville Police found 47 shell casings in the possibly targeted shooting.

“These shootings mark the most significant surge in gun violence here since 2022,” DA Marian Ryan said in a statement. “The fact that over 50 shots were fired in very densely populated areas, some in the middle of the afternoon, is the type of brazen, dangerous conduct for which those responsible must be held accountable.”

“We have committed substantial resources over the past several years to address every instance of gun violence in this county through prosecution, prevention and legislative action,” Ryan said.

The first reported shooting was in Cambridge at 2:15 p.m. on Monday. A police officer reportedly saw and responded to the shooting in the area of Bishop Allen Drive and Columbia Street.

Two people who don’t know each other reportedly were arguing. During the altercation, a male wearing a mask fired multiple gunshots at the other party.

No one was injured in the shooting. Following the incident, Cambridge Police were able to identify multiple juveniles suspected to be involved in the incident.

One juvenile male was arraigned Tuesday on charges of possession of a large capacity magazine and ammunition.

A second juvenile has been charged with assault and battery on a police officer, and defacing property for throwing an object at an officer and damaging items in the interview room at the Cambridge Police Department.

Also on Monday at 9:15 p.m., Belmont Police responded to a call of shots fired on Clark Lane. The preliminary investigation suggests that the victim and his son were outside an apartment complex when a vehicle sped by and opened fire, striking the man in the leg. Police recovered multiple pieces of ballistic evidence at the scene.

Then just after midnight on Tuesday, Somerville Police responded to multiple 911 calls of shots fired in the area of the Clarendon Towers, located on Broadway.

Upon arrival, officers found 47 shell casings and other ballistic evidence. A man, who was possibly targeted, was outside an apartment complex when a vehicle pulled up. Multiple people allegedly got out of the vehicle and began firing in his direction.

The Middlesex District Attorney’s Office is investigating all three incidents in partnership with Cambridge, Belmont and Somerville Police, in addition to the Massachusetts State Police.

Investigators are asking anyone with any information to contact their local police department or the Massachusetts State Police Detective Unit assigned to the District Attorney’s Office at 781-897-6600.