A threat on social media saying the poster would “shoot up” Kapolei Middle School on Friday resulted in most students staying home and police patrolling the campus all day.

The scare at the West Oahu school came in the wake of one of the nation’s deadliest school shootings on Wednesday. In Parkland, Fla., 19-year-old Nikolas Cruz killed 17 students and teachers at his former high school, law enforcement officials said.

“This is a situation that we just don’t take lightly,” said Donalyn Dela Cruz, state Department of Education spokeswoman.

The threat was made Thursday on Instagram with a message from an individual saying he or she planned to “shoot up” Kapolei Middle at 8:30 a.m. Friday. The post has since been removed.

Police have initiated a first-degree terroristic threatening case. No arrests were made as of Friday afternoon.

School administrators said students who make such threats face serious penalties from detention to dismissal and possible arrest and criminal charges.

In a letter being sent to parents and guardians of Kapolei Middle students, state schools Superintendent Christina Kishimoto encouraged parents to talk with their children and “emphasize the seriousness of these types of threats.”

According to police, first-degree terroristic threatening is a Class C felony that carries a penalty of up to five years in prison.

School administrators immediately alerted police once they learned of the threat. Parents of Kapolei Middle students also were notified prior to school hours.

The threat rattled many parents who opted to keep their children at home.

A total of 644 students who were scheduled to be in school Friday were listed as absent, compared with 524 students who went to school, according to Dela Cruz.

When students arrived on campus, a “modified lockdown” took place where students had to stay in classrooms.

In a lockdown, no one is allowed to enter or exit the campus. In this instance, Dela Cruz said, parents were allowed to enter the campus to either drop off or pick up their children.

Police were observed patrolling campus grounds Friday morning. Police vehicles were situated in front and to the side of the school. FBI agents also reportedly assisted.

The modified lockdown was lifted at about 9:15 a.m.

“Right now there’s no imminent danger to the campus. Honolulu police will remain on campus all day,” Dela Cruz said.

Kishimoto said, “The horrific event that occurred at Marjory Stoneman High School in Florida has had an impact on many parents, teachers and students. Across the country, school districts are dealing with rumors or threats against school safety that is spread via social media.”

“The Hawaii State Department of Education (HIDOE) is no exception. When a school administrator becomes aware of a threat, police are immediately notified and an investigation is launched,” she said.

“The safety for students and staff are top priorities for HIDOE schools,” Kishimoto said in the letter.