Texas High School Student Punches Teacher in Face, Video Angers Parents

A high school student in Texas punched his teacher square in the face ... a frightening encounter captured on video.

The violent outburst happened at Lamar High School in Houston, where footage shows a student arguing with a male teacher who had, apparently, taken the kid's phone for some reason -- then suddenly the student threw a haymaker.

They were face-to-face when the teen reached back and uncorked a right hook, landing flush on the teacher's jaw. Shocked onlookers screamed as the student threw more punches, and the video abruptly cuts off.

Students are sharing the video all over social media, and parents with kids at the school are obviously outraged.

The school's principal reportedly sent a note to parents saying the school does not condone or tolerate this type of behavior. The principal says, "Administrators will be looking into the cause of the altercation and continue to evaluate ways to prevent these occurrences in the future."

The teacher hasn't been identified by name and hasn't publicly commented about the incident.

It's another example of the increase in student violence against teachers in schools across the country ... a subject we dove into on "TMZ Live" with Lt. Rudy Perez, the head of the National Association of Resource Officers.