A juvenile authorities believe is linked to a social media threat about a school shooting at Casa Grande High School was identified and arrested at his Petaluma residence Thursday morning, police said. There is no active threat and school is in session, school officials said.

The investigation into the origin of the posting, possibly made on Snapchat, began around 9:30 p.m. Wednesday, Petaluma City Schools District spokesman David Fichera said. Reports poured into the police department from 15 different parents, students and citizens concerned about the posting, according to a news release.

An initial investigation determined the threat was not credible, though police continued to look into the incident using “an abundance of caution,” according to a news release from the department.

Officers worked in conjunction with school staff to contact “several juveniles” before locating a potential suspect at his home around 8 a.m., police said. He was interviewed by detectives and arrested on suspicion of a felony of threating a crime with the intent to terrorize, police said.

The juvenile and his parents cooperated with the investigation and no firearms were located, police said.

Fichera declined to say if the suspect was a student at Casa Grande or to provide any other details.

Further information about the nature of the threat alleging a Thursday shooting, which would have fallen on the anniversary of the Columbine massacre, were not available. It was unclear if the threats were inspired by the 1999 massacre at Columbine High School in Colorado, where two students killed 13 people before killing themselves, Fichera said.

School administrators sent an email to parents of all high school students Thursday morning to alert them about the investigation. A second email was then sent to the entire district, Fichera said.

“We take any rumors or discussion of any possible threat to the safety of students very seriously as seen in our quick action. We coordinated with local law enforcement as needed to come to a quick resolution,” he said. “Anything concerning the potential risk to our students we take very seriously. I’m glad in this case that there was not actual threat to students or the school. It also provides us an opportunity to work with students about the importance of responsible use of social media.”

The social media posting appears to be an isolated incident, Fichera said.

Fichera said the investigation has been turned over to police. No further information was available from the department.

Anyone with information or saved images of the original threat is encouraged to contact the Petaluma Police Investigations Unit at (707) 778-4415.