Campus police received an email threatening "violence" around 2:10 p.m. and posted a tweet at around 3:50 p.m. advising that people who are not on campus should stay away. Details surrounding the nature of the email were not immediately available.
The female suspect, who is believed to be a student, had an appointment at the Student Success Center on campus, which is where the investigation was focused, according to CSULB police Chief Fernando Solorzano.
The suspect was taken into custody without incident, Solorzano added during a Monday evening press conference.
Shortly after 4:20 p.m., campus police posted an updated tweet saying the situation was "all clear" and that the shelter-in-place order had been lifted.
Authorities said there was no ongoing threat, and the campus was open for normal operations.
CSULB BeachALERT! The situation is ALL CLEAR. Shelter-in-place orders have been lifted. University Police currently have the sole suspect in custody. There is no ongoing threat, and the campus is open for normal operations. #CSULB— CSULB Police Dept (@CSULBPolice) October 7, 2019
Many students took to social media during the temporary lockdown, saying that their classroom doors would not lock. Video posted on social media show desks piled against a classroom door and a belt tied up above.
"Our classroom is really old so they actually couldn't lock so we had to like prop a chair against the door," said Millie Nguyen.
By early evening, a petition started asking people to sign it if they believe university campuses need to have locking doors to protect their students from an active shooter or other threat.
A spokesperson for the university said it is investing $500,000 to retrofit classroom doors so that they are able to lock.
The name of the suspect has not been released. Police believe the suspect was acting alone.