LEBANON — Students remained in their classroom, activities room, auditorium and even locker room while police detained a 39-year-old man outside Lebanon High School and Hanover Street School on Friday afternoon.

The incident, in which police confiscated four firearms from the cab of a pickup truck, offers a glimpse into the protocols schools follow in the event they are confronted with a potential threat.

Instructed not to talk on their phones, students texted family members, friends and teachers as they received and shared information of the incident unfolding outside their school, expressing love and supporting each other, parents said on Monday.

“My biggest takeaway is that the system worked,” said Naomi Wimett Hastings, a Grantham mother of two students — a 15-year-old sophomore and a 17-year-old junior — who attend Lebanon High School. “And that’s how those systems are supposed to work.”

Hastings, who is married to Grantham Fire Chief Justin Hastings, said she first learned that something was going on at the campus when, on a walk to the nearby Jiffy Mart to get a snack, her 15-year-old texted her to report: “Something is going down” at the school because they had just seen “eight police cars” speeding past.

Meanwhile, her 17-year-old was inside the high school’s music room for band practice, and the three of them engaged in a group text chat because students inside the school were instructed not to talk on their phones, Hastings said.

Over the weekend, Lebanon school officials sent emails to parents notifying them that “as a precaution” extra counseling support was being made available to students and staff, and the public would see a beefed-up police presence around Lebanon schools, in addition to seeing “members of the district administration at all campuses.”

“This incident understandably has caused anxiety for students, their families and staff,” Amy Allen, superintendent of SAU 88, said in an email to parents on Sunday. “The safety of our schools is of the utmost importance, and we have zero tolerance for behaviors that threaten the safety of the school community.”

Allen further said that this week “all our teams will evaluate and review” their joint response to the incident.

Events started Friday afternoon when Lebanon police intercepted a 39-year-old Vershire man in his pickup who they said was experiencing a mental health crisis and had earlier threatened to harm himself. The man was arriving at the school to attend a weekly singalong session with his grade-school-aged son.

Lebanon Police Chief Phil Roberts credited the school’s resource officer, Gregory Parthum, with being a key link in connecting the original call from the man’s ex-partner to a police response.

“This is a great example of the relationships that the school resource officer makes not only with students but with faculty and parents,” Roberts said on Monday. “This parent felt comfortable enough through her previous contacts with the SRO to call him directly and say, ‘Hey, this is what’s going on. I’m not getting the help’ ” from police in Vermont whom she called first “ ‘and I need your help.’ ”

When Lebanon police stopped the pickup truck on the school’s perimeter for a “welfare check,” they found four firearms in the truck and said the man had been was “non-compliant” for more than two hours as they tried to coax him out of the cab.

Police took the firearms into their possession and transported the man to Dartmouth Hitchcock Medical Center for evaluation.

He faces charges of disorderly conduct and resisting arrest, both misdemeanors, and is scheduled to appear for arraignment in Lebanon District Court on April 29.

According to the bail order, the man was ordered not to have any contact with either his ex-partner or their son and is also barred from possessing firearms, consuming alcohol and must stay 300 feet away from any school.

The bail order shows the man was released on personal recognizance.

In an email to parents, Tom Harkins, principal of Lebanon Middle School, urged parents to ask their “students to be respectful of the family involved in the incident, and to not joke and/or gossip about it.”

Hastings, the parent of the two high school students, said the first 10 minutes between the first alert and the following update providing more information were probably the most stressful. Her 17-year-old reported receiving “15 texts in eight minutes” from friends, alternating between asking “are you OK?” and messages of “I love you.”

“As much as they were concerned about safety in the high school, there overriding concern was the little kids,” Hastings said.

The high school and elementary school are on the same campus but separated by the gymnasium.

“There was a sense of, ‘We’re the big kids. We got to protect the little kids,’ ” she said.

Nikkea Kimball, a manager of an apartment complex in Lebanon who has a 5-year-old daughter in kindergarten at Hanover Street School, said she was at work in her office on Friday when she saw an alert on Facebook not to go near the school.

She immediately began texting with other parents to learn information about the situation.

“The school is pretty good communicating at what is going on,” Kimball said.

Her daughter was in the same singalong with the son of the man who was arrested, but she said her daughter was never aware of what was going on outside the school. The “kids just stayed in the auditorium” for the more than two hours until the all-clear signal was issued about 4:30 p.m., she said.

“Honestly, she was just exhausted,” Kimball said of her daughter when she came to pick her up at the school. “She fell asleep in the car on the way home.”

Contact John Lippman at jlippman@vnews.com.