Fairfax County police officer Lou Munoz has been patrolling the hallways of Westfield High School — “the front lines,” as he calls them — for eight years. He oversees the safety and security of 2,800 students. On any given day, he might deal with a traffic accident in the student parking lot, break up a fight in a classroom or arrest a teenager for possession of marijuana.

“There’s only one cop there, which is me,” Munoz told an audience at the Sully district police headquarters. “There’s a lot happening daily.”

There are 54 school resource officers (SROs) at Fairfax County schools, including one posted at every middle and high school. Munoz has been a Fairfax police officer for 21 years and describes his beat at Westfield as one of the most difficult and most rewarding.

“You wear a lot of different hats as SRO,” said Munoz, who is also Westfield’s junior varsity baseball coach. He said he prefers to build relationships with the students so he can prevent the teenagers from getting into trouble, leaving discipline for the rare times when they stray.

“That way, they feel like they are letting me down if they keep doing it,” Munoz said.

Perhaps the most distressing aspect of teen life these days, Munoz said, is the way the students interact on social media, particularly Twitter.

“Almost every day I have kids coming to me about cyberbullying,” Munoz said. “Kids aren’t on there saying, ‘Oh wow, Sally’s pretty. She wears nice clothes.’ No. They are trashing each other.”

Munoz advised parents to “be proactive” in their children’s lives and to ask questions about behaviors. “Don’t give up on your kids,” he said.

The recent mass school shooting in Newtown, Conn., has refocused attention on school security, and SROs are at the center of the discussion about how best to keep students safe.

“A safe and secure environment is a prerequisite to learning,” said Jim McLain, a security coordinator for Fairfax County Public Schools. “It’s a daunting task. We’re strapped for resources but we do well.”

McLain, a retired Fairfax police officer, said that when he first joined the force, “every door in every school was open.”

Today, schools in Fairfax County are equipped with electronically controlled entrances and specialized security systems.

“We have cameras, but we don’t have enough,” McLain said. “Technology is not a panacea, but it is a deterrent.” McLain said the best security measure for schools is parental involvement, because “we’re all in this together.”