Additional security patrolled both Belleville high school campuses Friday afternoon in response to the deadly school shooting at an elementary school in Connecticut.

"We have a pretty involved security plan, lots of cameras on campus and a school resource officer," District 201 Superintendent Jeff Dosier said. "Normally, we have three security patrol persons plus a resource officer on each campus, but we're bringing in two more for each campus."

A gunman opened fire Friday morning inside a school in Newtown, Conn., killing 20 children and six adults. The shooter was identified as Adam Lanza, whose mother worked at the school. Lanza committed suicide at the scene.

Dosier said he is "pretty confident" in the security at the campuses of Belleville West and Belleville East high schools.

"In instances like this, I'm not sure the best security in the world can prevent this," he said. "Obviously, our focus is the security and safety of our students and staff."

Most schools have a series of security measures in place, including a buzz-in system where school officials can identify a visitor through surveillance cameras before they are allowed to enter a building.

Belle Valley School District 119 Superintendent Lou Obernuefemann said students in his district benefit from learning in one of the most secure buildings in the metro-east.

Belle Valley School, which opened in 2011, only can be accessed through one entrance. Visitors have to be buzzed in by a staff member who can see them through an extensive video camera system. Once they get through the first set of doors, the visitor can go to the offices. But they have to be buzzed through a second part of the school to get to the main part of the building where students are located.

"The entire building is basically locked down," Obernuefemann said Friday. "That's one of the best things about having a brand new school."

Despite social networks being filled with parents' comments that they want to go get their kids from school to make sure they're safe at home, Obernuefemann said no parents called early to ask whether they could come get their kids.

While not all districts can afford new schools, districts with older buildings have done their best to retrofit them, local school officials said.

In Belleville District 118, some buildings are the better part of a century old. Still, all doors are locked and visitors must be buzzed in after identifying themselves. District 118 Superintendent Matt Klosterman said that school district staff spent the day reviewing its crisis management plan.

"This allows us to step back and review how we're doing with that and analyze our carrying out those procedures," he said. "We have a system in place where the main entrance of each school and each building is generally secure throughout the day."

Klosterman said school leaders decided not to tell children and, instead, made a decision to let their parents decide how and whether they want to discuss the issue with their kids.

"We will have some follow-up discussions on Monday with our staff to see if there is anything that needs to be addressed," he said. "We have to weigh that with reviewing what our procedures are and not get our youngsters too upset when we don't need to. That's a balance we have to set."

Klosterman also said the school district has social workers available for support and to counsel students, if needed.

"In this case, it's a bit far removed, but it certainly hits home because it occurred in a school, although halfway across the country," Klosterman said. "It's unlikely any of our students knew anyone from there. If any of our student indicate that they need some support with this, then we would be able to make our staff available, but we haven't had any conversations about it because it is all still unfolding."

In Collinsville's District 10, leaders did not tell students about the shooting.

"Normally, we wouldn't tell the students something like this, because it would be upsetting to them, during the school day," said Superintendent Robert Green.

He said it is a subject that is appropriate for students to talk about with their families, when they feel safe.

Green, acknowledging that he is not a mental health expert, encouraged parents to talk about the shooting with their children but to let them know that they are safe and sometimes bad things happen without reason.

He also encouraged parents and grandparents to contact their child's school principal if they feel the student needs to talk to someone.

"Sometimes what seems like a trivial thing to an adult could build up in a child and they need to talk about it," Green said.

Edwardsville Community Unit District 7 Superintendent Ed Hightower met with the high school principal, assistant superintendents and school security officers Friday afternoon.

The district employs multiple security avenues, including all visitors signing in and showing identification and school security officers patrolling the high school and middle schools, but Hightower said they continue to examine safety on campus.

In a letter to parents and staff, Hightower said: "When such an act of violence occurs, it causes us as a district to reassess our current safety measures. With only a few days before the holiday break, I want to reassure parents that District 7 will continue to take every precautionary measure to protect the safety of our children."

"We're going to go back and look at every measure we're taking, particularly to secure the building," Hightower said.

"I don't know if metal detectors would be the answer," Hightower said. "If somebody really wants to get in and ... take lives, as in the East, they would still do it ... but we will continue to keep all options on the table," he said.

He said district leaders will discuss the shooting and security at Monday's school board meeting.

"It's just, gosh, such a tragic ... my heart goes out to the families of that school," Hightower said. "We will have a moment of silence on Monday morning in every building. We will hang our flags at half-staff. We will do whatever we can to support the families of this school. And at the same time, we will continue to ask the question: Are we doing everything we can to keep our schools safe?"

In Springfield, Gov. Pat Quinn said: "I am shocked and deeply saddened to learn of the horrific massacre that occurred today at Sandy Hook Elementary School in Newtown, Conn.

"All of Illinois prays for the victims of this senseless violence and their families. May God bless the immortal souls of all those who lost their lives. In their remembrance, I have ordered all flags across Illinois to be flown at half-staff beginning today."

Quinn added: "It is the foremost duty of government to protect public safety, especially the safety of children and students. As governor and as a parent, I intend to spearhead passage of strict laws that will protect our children and the people of Illinois from gun violence."