The girl was assaulted around 11 a.m. near Monroe High School. Authorities said the suspect took off his shirt and covered his license plate with it. He then removed some more of his clothes, charged at the girl and grabbed her buttocks. When she screamed, he ran away.
The suspect was described as a man in his 30s, standing about 5-feet 6-inches tall and weighing 150 pounds. He had a thick mustache and was driving a compact red car.
Investigators believe the incident is the latest in a string of attacks near schools in the area. Earlier this month, similar assaults happened near Arleta High School. A suspect sketch in those cases has been released.
Officials said in nine cases, a man approached girls or committed lewd acts in front of them. In at least two of the incidents, the suspect tried to kidnap the girls.
"Whether it happened here at Monroe, North Hills, or Arleta High School, we're still issuing safety alerts to students to be vigilant, to walk in groups, if anyone may attack them or they feel that someone is watching them to scream for help or run into a nearby school," said Monica Carazo a Los Angeles Unified School District spokeswoman.
Students said they're more aware of their surroundings after hearing of the incidents, but are still uneasy on their walks to and from the schools.
"It makes me really nervous because I walk after school so I'm kind of paranoid now, and my mom's nervous too," said student Rebecca Zeraldi.
Anyone with information was asked to call the Los Angeles Police Department at (877) LAPD-24-7.