Several school districts in Northern California fell victim to a nationwide social media trend threatening schools Friday.
In the North Bay, the Tamalpais Union High School District in Marin County canceled classes at all schools after the district's main office received a threat of violence around 7:30 a.m. via text.
Shortly after receiving the threat, the district's five schools evacuated the campuses and contacted local law enforcement. District officials said the threat didn't name which school or target site. They didn't specify the danger, but a spokesperson did tell KTVU that the threat was not a shooting.
At the time, district officials said students should remain home and those on the way or at campus should return home as they closed down the schools.
An all-clear was announced hours later when district officials said police searched and cleared all schools and offices in their district.
On the other side of the North Bay, Fairfield police said they, with the Fairfield-Suisun Unified School District, were aware of the social media trend of threats to schools and said they were not credible.
"Despite the social media post's circulation in Fairfield and other Bay Area communities, there's no credible connection to our local community or FSUSD schools," Fairfield police said.
Police said despite the threat not being credible, officers and district personnel were present.
Also in Solano County were threats made to Vacaville Unified District Schools, Vacaville police said.
District Superintendent Ed Santopadre addressed the concerns, saying the district worked closely with Vacaville police and found the threats also not credible.
"Unfortunately, a national social media trend involving alleged threats to school campuses is impacting schools across the country," Santopadre told community members in a letter.
In the South Bay, a threat was made shortly after 7 a.m. to Mt. Pleasant High School in San Jose on social media, according to the San Jose Police Department. Police increased patrol checks at the school.
Outside the Bay Area, Sacramento police shared a notice that they were aware of the trend threatening schools, and shortly before 11 a.m. in Tracy, a bomb threat was made to North School and Williams Middle School, police said.
Police conducted security checks on the campus, and found the threat not to be credible after the search.
"These threats are against the law, and anyone making any threats will be disciplined and prosecuted to the highest extent of the law," Tracy police said.
Earlier in the week, Casa Grande and Petaluma High Schools in Petaluma were threatened with acts of violence that would occur on Friday afternoon.
Police received several reports but said they did not think the threat was genuine.
"Outside of the social media post, there has been no information that leads us to believe that the threat is credible," said the department in a Wednesday night release. "However, the Petaluma Police Department treats all threats seriously and will be diligently investigating the incident thoroughly."
The Petaluma Police Department provided an extra police presence at each of the involved schools.
The Fairfield-Suisun Unified School District and East Side Union High School District did not immediately respond to KTVU's request for comment.
This story was reported out of Oakland, Calif.