A gang attacked a man and then went on to wreak havoc in Vista Hermosa de San Rafael, Oreamuno, Cartago, Sunday night.
The first police on the scene were greeted with rocks, so the Unidad de Intervención Policial, the riot squad, was called in.
In the midst of the melee police said someone fired a shotgun several times.
The marauders sacked several homes in the area and stole possessions. At least one vehicle had a window shattered. At one home the rioters stole a marijuana plant.
Eventually police detained seven persons, and two turned out to be juveniles.
The origin of the gang activity still is being investigated. Police said they retrieved some of the stolen items and also confiscated the shotgun.