Roaming danger

Recap:greg a 17 year old arrongant and self obsessed teenager, had a argument with his single mom in the mornibg before leaving for school, meanwhile in the school in his moral science lecture he realizes he has beem rude to his mom so he decides apologize ,saying sorry is the thing at which greg is extremely bad at it hurts his little ego to say to anyone , but going downstair after the school gets over with his teacher and five other students namely nia(genius prospect),chadwick(kind hearted rich guy),james(sporty tall boy),miss bella(moral science teacher) ,melissa(beautiful introvert girl), and finds something wrong ,they all were late in leaving the class and they find everyone to be eating flesh and acting like brain dead creatures zombies,they all rushes to classroom melissa falls on the ground and injures her leg ,greg who could have help ignore to help her running for his own life,james who have reached the class ran to safe melissa and pushes melissa in the class but fails to make it to the class and ran straight with zombies behind him , meanwhile they all discuss what to do suddenly the windows broke out and zombies enter the classroom...

Now....
As the zombies are brain dead they only react to what they see moving or what they hear moving , they all gather at the corner of the class trying to maintain pin drop silence,but accidentally melissa couldn't control her sneeze ...and the zombies start moving towards them .....a zombies comes towards them greg hit him on the face with a backpack another one came from behind and tries to bite greg ,greg using his martial techniques pull him off his shoulder and knocks him to the ground but they are too many coming ,....but wait suddenly the school bell rang making unpleasant sonorus sound and it was extremely unusual to see zombies feeling pain in their brain and trying to stop the sound and not attacking the kids....
The voice from loudspeaker of the...