The Boston Police Department reports a gun-toting man refused entry into the Lilla G. Frederick Middle School on Columbia Road by officers Monday afternoon snuck back in to continue an argument with somebody at basketball tryouts there.

On seeing officers again, this time outside the school gym around 3:45 p.m., the man and three accomplices tried running away, police say. Officers caught one of them, but the man and two others escaped - at least until officers on patrol on Devon Street noticed two guys matching a broadcast description from the school:

"Officers noted that one of the suspects was carrying a backpack. However, as officers approached, officers observed the suspect place the backpack on the ground, walk a short distance and then stop. Officers immediately ordered both suspects to the ground. A search of the backpack enabled officers to see and seize a firearm. Officers subsequently arrested the suspect, Dashaun Harris, 22, of Dorchester, and charged him with the Unlawful Possession of a Firearm."

The teen, Kwame Browder, 17, of Dorchester, was charged with trespassing, assault and battery on a police officer and resisting arrest.