UPDATE: The Petaluma Police Department said on Thursday that it believes the suspect who made the threat was not in California and the threatened school was not Casa Grande High School in Petaluma.

Read part of a statement from police below:

“The Petaluma Police Department’s Investigations Unit has been working diligently with the Federal Bureau of Investigation to identify the suspect, evaluate the credibility of the threat, and assess the safety of the school.  Based upon the information that has been discovered, we believe the suspect who made the statement was not in California and the reference to Casa Grande School was not Casa Grande High School in Petaluma.  The law enforcement agency in the appropriate jurisdiction has been notified.”

PETALUMA, Calif. (KRON) — The Petaluma Police Department and Federal Bureau of Investigations investigated a potential threat of violence at Casa Grande High School. The threat was made specifically for June 10, when the school will hold its graduation ceremony.

The Petaluma City School District confirmed the threat in a letter to families. Neither police nor the school district went into detail about what the threat entailed.

“We take all threats seriously, and we want to keep you informed and equipped with the information you need to support your children,” PCSD said. “It pains me to think that anyone in our community would make a threat like this. Any threat of violence weighs heavily on our community, and I know that our current national climate makes this news harder to carry than ever.”

PPD said it was working to determine the credibility of the threat and to identify potential suspects. The school district said no other schools have received threats.

Some students at Casa Grande told KRON4 that they are not completely convinced the threat is credible, but given the mass shooting in Uvalde, TX, it must be taken seriously.

“I think its kind of annoying because it happens a lot, and people actually go through with it,” one sophomore said.

Last week, Petaluma police tracked down a 13-year-old student at Petaluma Junior High for falsely reporting an armed man on campus. The student was referred to the police department’s restorative justice program.