Episode 9 of "Boston public"
s01e09 Chapter Nine

The first day back at school has barely begun when the police show up looking for a murder suspect. A botched robbery has gone down a few blocks away and the panicked assailant, wearing a Winslow High letterman's jacket, shot and killed a man before heading towards school grounds. The police think the suspect is a student who is hiding on campus and demand to begin the search at once. Meanwhile, oblivious to the tense situation, Lisa and Buttle decide to have sex in the deserted boiler room. Unfortunately, Riley and an officer stumble upon the couple during the investigation and catch them in the act. Riley agrees to keep quiet about the affair for now, but urges Buttle to break it off before he loses his job…or worse. As the hunt continues, it becomes a code red condition, locking both teachers and students in their classrooms. Eventually, Lauren realizes that a pupil in her class might be the suspect but before she can take action, the desperate student whips out his gun and takes Lauren hostage. The police immediately call in the SWAT team to stake out the area but Harper rushes into the classroom to talk the kid down. Principal Harper makes little headway and the situation is becoming extremely tense. Just then, Senate barges into the room and using his usual risky but courageous methods he manages to make progress with the frightened young man. When the suspect lets his guard down for a moment, Harry wrestles him to the ground freeing Lauren in the process and saving the day.