Kid arrested with loaded gun outside Dorchester school after he and two pals stomped another teen, police say

Boston Police report arresting a 15-year-old with a gun loaded with 13 rounds after he and two other teens beat up another teen outside the Joseph Lee School, 155 Talbot Ave. in Dorchester Monday afternoon.

Police say drug-unit officers conducting surveillance in the area of the school spotted three beating and kicking another teen around 2:10 pm.

After detaining the two 15-year-olds and a 17-year-old, they found one of the younger teens was packing a 9-mm gun with 13 rounds in a magazine, police say.

That teen, from West Roxbury, was charged with being delinquent for unlawful possession of a firearm and unlawful possession of a ammunition, police say. All three teens were charged with being delinquent for assault and battery with a dangerous weapon - a shod foot. The other two are from Dorchester, police say.