Several people, including teenagers, are killed in brutal ways throughout the movie. The violence is very bloody, and sometimes graphic, although not exceptionally gory.
A man grabs a girl from behind and slices her neck open with a knife; blood copiously pours from her mouth and neck and pools at her feet, as the killer keeps stabbing her in the chest. The girl's bloody body, with the gaping neck wound visible, is later found by a girl.
A man shoves a knife into the chest of a teenage boy. Blood pours from the boy's mouth and from the gaping hole in his chest; the man drops him to the ground and we see him bleeding. We later see the boy's dead body being loaded into a body bag.
A man finds his pregnant wife in a pool of blood on the bed (she appears dead). The man is then seen with blood covering his shirt and face, attempting to stab himself in the stomach as a little girl watches; he lunges at the girl with the intent to kill her with a knife, but is shot in the back before reaching her. A doctor injects adrenaline in him with a large syringe; the man wakes up and says that he heard a voice in his head telling him to kill his family. He shoots two men and is about to shoot a woman, but is shot again; one of the two men he shot is unharmed due to his bulletproof vest, the other was shot in the head and died. The killer lies on the floor with several bloody bullet holes in his chest, and is then shot in the head. Then the killer, presumed dead and covered in blood and cuts, is taken in an ambulance, where he wakes up, grabs something and cuts a woman's throat (blood pours from the wound); the driver swerves, the injured woman gasps for air and the ambulance runs off the road. The vehicle is on fire but the occupants are already out, unharmed. The killer is presumed alive after the accident.
A man rushes toward a teenage girl, her feet are seen being lifted off the ground, and we hear the slicing sounds and the girl choking with blood (offscreen), while blood sprays on her feet and pools on the ground, drenching the leaves; her body is seen being dragged away, and is later found with blood on it.
A man chases a teenage boy and attacks him, slamming his head into a metal pole, and then stabs him in the stomach (we see blood as the man tackles the boy). He then drops him in a river. His corpse in later found on the shore of the river, covered in bloody scratches and cuts.
A police officer holds a gun to a teenage boy who is holding a bloody knife (his hands are covered in blood). The boy drops the knife, and we see a dead woman lying in a pool of blood. The police officer asks the boy if he killed her; he says he didn't do it. Then the man starts handcuffing the teen boy, but is suddenly stabbed in the back by a man. The boy fights with the killer, who repeatedly tries to slice him with a knife. The boy crashes onto a table, then kicks the killer and drops a vase on his head; he then grabs the police officer's gun and fires at the killer several times, but always misses. The killer attacks him again, and the boy has two bloody cuts in his back. The killer then knocks a girl, who falls unconscious to the ground, and keeps attacking the boy with a knife, but then he hears a noise and runs away. The boy chases him with a large knife in his hand. Then he slowly opens a closet door, and a teenage boy stumbles out and falls to the ground; he has a large bloody wound on his chest. He gasps and dies as the other boy watches. Another boy arrives, and after a talk the two have a fight. One of them punches and kicks the other while threatening him with a knife. They struggle, and one of them is stabbed by the other in the stomach, dying shortly after.
An angered teenage boy shouts at a girl, as he chases her through a wooded area; the girl stumbles and after standing up appears to have trouble walking (we see her back covered in blood, but there are no visible cuts).
A teenage boy has a vision of a dead girl; she has a gaping bloody wound on her neck, and is drenched in the blood that came out from her face and mouth.
A teenage boy punches another boy in the stomach, knocking him to the ground, and then punches a third boy in the arm.
A man shouts at a teenage boy, and then punches him in the torso; we later see a large bruise on the boy's stomach.
A teenage boy slaps another boy in the face.
A woman slaps a teenage girl.
A girl punches a boy hard; his nose bleeds. She then hits and kicks him.
A teenage boy stumbles and falls into the shallow bank of a river, as he runs to avoid a group of police officers.
A teenage boy wearing a bird-costume terrorizes his classroom, then spews a vomit-like green substance onto another boy, who punches him. The boy in the costume then pulls a cord that releases a brown fluid from the costume's behind, implying defecation. The other boy hits and kicks him, knocking him to the ground, until he is pulled away by the teacher.
A teenage boy tells another that he had killed a man accidentally; he describes how he had fought back after the man started beating him, and how the man fell down the stairs and broke his neck (we do not see it happening).
A man and a woman discuss the murder of a teenage boy's mother with him.
A teenage girl explains to a teenage boy that his father did not die in a car accident, but was a serial killer that killed their mother.
A teenage girl tells a woman that the bodies of three dead teenagers had been found.
A teenage girl tells another girl that a boy had killed people in the past and spent time in mental hospitals.
A boy tells a woman that he had to "bury a friend"; the woman asks him if he had killed a person, and the boy says he was only burying a crow "puppet" that had been "killed".
A woman watches a television programme where we see a man grabbing a person from behind and holding a knife above their head; the television report explains that the man in the video is a serial killer, who has not been caught yet.
On multiple occasions, teenagers discuss how they need to fear for their lives because a serial killer had been murdered on the day of their births, and might come back to stalk and kill them.
A girl instructs a teenage boy to punch two others with varying levels of force.
A teenage boy jokingly tells another that he is going to burn down a house with a man inside.
A boy gives a speech to a classroom of teenagers describing how California Condors "eat death," including corpses crawling with maggots.
We see a flock of crows attacking a group of children in a movie on TV.