Police say two Stamford teenagers were injured Friday afternoon in after-school fights between two feuding groups of students.

Police say one teen was hospitalized with a serious head injury and is in critical but stable condition. The fights broke out in a parking lot off Strawberry Hill Avenue around 2 p.m. Friday. According to authorities, when they arrived, the teenage boy was convulsing on the ground.

Witnesses and surveillance videos aided police officers in tracking down and arresting two suspects involved in the fight.

Police say a second fight broke out, which injured another teenage boy. According to authorities, the boy was punched in the face and may have to undergo facial surgery. Officers arrested another minor in conjunction with the second fight.