About 3:25pm on Wednesday June 3, 2026, Officers of District B-3 (Mattapan) made an onsite firearm arrest in the area of River Street and Topalian Street, Mattapan.
Through shared information, Officers of District B-3 were made aware of a possible illegal firearm possession in the area of River Street and Topalian Street. Officers were given a description of a male, wearing a black canada goose knit hat, black surgical mask, grey sweatshirt and black sweatpants. Officers were also aware that the male was in possession of a black firearm in his waistband.
With prior information, Officers remained in the area, and observed a male matching the aforementioned description, exit his residence in the area of River Street and Topalian Street. Officers observed the male, walk to the corner of River street, then take notice of officers and immediately walk back into his residence. Moments later, Officers then again observed the male exit his residence, and walk the opposite direction, on to a dead end street. After taking notice of officers again, the male turned around again and walked back into the residence. The male then left the residence again in the same direction as his initial exit.
After several additional observations, Officers began to approach the male, which resulted in a foot chase. Officers made several observations throughout the foot chase, which led officers to believe the male was in possession of a firearm. When turning on to Topalian Street, Officers observed the male retrieve a black firearm from his front waistband, and immediately throw the firearm onto the sidewalk at the corner of River Street and Tesla Street.
Officers were able to safely apprehend Shawn Allen, 18-years-old of Hyde Park, in the parking lot of 535 River Street. Officers and District Detectives located a black firearm at the intersection of River Street and Tesla Street.
The firearm was determined to be a Taurus G3C 9×19 loaded with 10 live 9MM rounds and 1 live 9MM round in the chamber. A query revealed that the firearm was stolen out of Quincy, Massachusetts.
Shawn Allen will be charged in Dorchester District Court with the following:
MGL 269 s.10a & d Unlawful Possession of a Firearm
MGL 269 s.10n Unlawful Possession of a loaded firearm
MGL 269 s.10h Unlawful Possession of Ammunition without FID card
MGL 266 s.60B – Receiving Stolen Property
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