The following article contains an answer for the question: Who is murdered at the scene that the classmate is running from? , can you please find it? 

In June 2012, 18 year old high school graduate Jesse Arista lives with his father, sister and grandmother in Oxnard, California. He begins to enjoy the summer with his best friend, Hector. In the apartment below lives a mysterious woman named Ana, who everyone believes to be a witch. When Ana is found murdered, Jesse and Hector spot classmate Oscar running from the scene, suggesting he was responsible. The two investigate the apartment, where they find black magic items, as well as VHS tapes and a journal of spells that can "open doorways to unholy lands."
After Jesse, Hector and their friend Marisol try out a ritual, paranormal occurrences gradually begin to take place in Jesse's apartment. One night, the trio begin to communicate with an unknown entity through a game. Jesse finds a mysterious bite mark on his arm and also discovers he has superhuman abilities, which is proven when he knocks out two thugs that assault him. He and Hector at first view his abilities as a "gift". At a party, Jesse takes a girl to Ana's apartment to have sex and encounters Oscar, who has black eyes and a similar bite mark on his arm. He tells Jesse that it's only a matter of time before "something inside them" will take over, and if they kill themselves, they will not harm those they love. Oscar rushes and disappears; when Jesse and Hector search for him outside, Oscar commits suicide by jumping off a building, landing on a car.
The group discover a secret trapdoor in Ana's apartment, where they find a witch altar and photos of Jesse, his pregnant mother, Ana, Oscar, and Lois. At the same time, a strange woman in black enters, but leaves after finding nothing. Jesse is lured to the trapdoor one night after hearing his dog Chavo barking for help, but the door slams shut and Jesse sees the ghostly figures of young Katie and Kristi before being attacked by a roaring demon.

Ana