Click in the Eyewitness News Story Window above to watch Subha Ravindhran's report from Lincoln Middle School
The investigation began on Friday when a 7th grader told her parents that she was sexually assaulted several times, said Santa Monica Police Dept. Lt. Dan Salerno.
One of the four girls may have been abused for up to a year, police said.
"Sometimes [my daughter] comes home and she talks about the teachers that are acting a little weird, but something like this is really scary," said Farima Sassoon, whose daughter is an 8th grader at Lincoln Middle School.
Beltran taught English as a second language classes for twenty years.
Police are asking any other victims to come forward. If you have any information, call the Santa Monica Police Dept. at (310) 458-8491.
Beltran is being held on $1.1 million bail.