More than two dozen teenagers were arrested, and hundreds were sent home, when police locked down Chester High School after a brawl that got out of control yesterday, Chester police said. Two teenagers were arrested on criminal assault charges after they attacked a police officer who responded to the fighting, police said. Twenty-six students were arrested for disorderly conduct and failure to disperse. Police said the students, all under 18, were released to their parents pending a hearing in juvenile court.