Torrey Pines High School was put on lockdown Thursday morning after an online threat.
San Diego Police confirmed that there was no active shooter on campus, but the school was placed on lockdown as a precautionary measure.
Students were released from classrooms in the early afternoon, but all school activities were either canceled or postponed for the rest of the day.
Police are now turning their attention to who was responsible for the threat. It reportedly came on the website Yik Yak -- a social media site and app that allows users to anonymously make postings to others within a 1 1/2-mile radius.
Police responded around 10:25 a.m., blocking off entrances to the school. Teachers kept students in their classrooms as police went through each room. The first students were seen leaving classrooms just before 1 p.m.
Despite the police presence, dozens of parents lined up outside the school.
"As a parent, I’m obviously concerned about the situation here and we want to know how it resolves as soon as possible," said Robert Margolis, the parent of one student at the school. "I talked with my wife and she asked me to come down here and see how it is, if there’s anything we can do."
School principal David Jaffe sent a letter to parents on Wednesday morning that read:
"We received an anonymous threat to school posted on Yik Yak. We have initiated lockdown procedures and are working directly with law enforcement at this time. This is a precautionary lockdown. As we need law enforcement to have open access to the campus we request you do not drive to campus until you are notified to do so. We will be posting updates on the school website. Again, this is precautionary."
Just after noon, the school posted a message on its website about the situation:
"On the morning of Thursday, November 20, 2014 Torrey Pines High School administration was made aware of an anonymous threat that was posted online. In consultation with the San Diego Police Department, the school was placed in lockdown status as a safety precaution. District and school staff are working closely with SDPD to ensure the safety of everyone on campus and to investigate the source and credibility of the threat. TPHS families have been apprised of the situation via email and phone messages and will be updated throughout the day. We ask that parents do not come to or call the campus unless directed to do so as this distracts law enforcement and school staff from ensuring the security of the campus."
The school is located at 3710 Del Mar Heights Rd., just east of Interstate 5.