LOS ANGELES -- Classes were canceled Tuesday for the Los Angeles Unified School District due to an unspecified threat, school and law enforcement officials said.
An "electronic threat" received early Tuesday prompted the decision, school district police Chief Steve Zipperman said, adding that the threat "is still being analyzed."
Ramon Cortines, the school district's superintendent, said he decided to call off classes for all students "based on what has happened recently and what has happened in the past." He said the threatening "message" was made to "many schools," none of which were identified by name.
"It was to students at schools," Cortines said of the threat, which he characterized as "rare."
Some of the details of the electronic threat — which was against “many schools” — included the involvement of backpacks and other packages, Cortines said at a morning news conference. The nature of the threat was “electronic.”
The Los Angeles United School District is one of the biggest in the United States. During the 2011-2012 school year, it had more than 660,000 students in kindergarten through 12th grade, plus more than 250,000 in adult education programs.
The superintendent said he's asked all schools to be searched thoroughly. He and school board members then will decide whether or not classes will resume Wednesday. Anyone at a school building when the notice went out around 7 a.m. PT (10 a.m. ET) Tuesday were asked to go home.
"I'm not taking a chance to bring (students into a school) until I know it is safe," Cortines said.
This is a developing story.
The CNN wire contributed to this report.