Officials say a teen has been charged in the fatal stabbing of Khaseen Morris in Oceanside.

They say 18-year-old Tyler Flach, of Lido Beach, has been arrested and charged with murder in the second degree on Wednesday.

Police say upward to 70 people witnessed the brawl at a strip mall near the high school where 16-year-old Khaseen Morris was stabbed on Monday.

Police say the fight was between two groups and may have been over a girl.

Keyanna Morris says the trouble began when Morris, her brother, walked a girl home Monday afternoon. She says from what she's been told by officials, the girl's former boyfriend started the fight with her brother.

Cellphone video captured the teens fighting outside of a pizza parlor on Brower Avenue.

Morris' three siblings and dozens of others visited his makeshift memorial near the spot where he was killed. His siblings wore shirts and bracelets that belonged to him.

Police patrolled Oceanside High School Wednesday, where Morris was a student, after numerous social media threats were made.

The online threats stated that neighboring high school kids were going to come to the school to respond to Morris' death.

"Every social media threat is considered serious. We investigate it all until it's deemed not serious. At this time, we don't find any credible evidence that there is any type of threats to the students or faculty in the school. At this time, the school is open," said Det. Lt. Richard Lebrun.

The school says that police have the names of the students behind the social media threat.

"It's scary thinking about this. It usually doesn't happen here," one student told News 12.

In a video posted online, Superintendent Phyllis Harrington addressed the concern that some students and parents had about the possible threats in social media posts.

"I ask in addition to using restraint and judgment on social media that you have a conversation with your children and that you monitor their social media usage," said Harrington.

Some students took the online threats so seriously that they decided to stay home from school.

There was also a visible police presence at neighboring Long Beach High School. The district postponed several activities this week, including homecoming activities because the school is close in Oceanside.

Long Beach schools told News 12 it does not know of any threats were directly aimed at the school or students.

Authorities say Flach will be arraigned on Sept. 19 in Hempstead.

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