Visitors to Birney Elementary School in Southeast Washington must identify themselves before a video camera at the main entrance and wait to be buzzed in, a dramatic new security feature that will be installed at all District elementary schools this year.

In Anne Arundel County, police, fire and school officials will stage a simulated crisis today at Chesapeake High School -- a training exercise ordered because of last spring's shootings at Columbine High School outside Denver.

In Loudoun County, a security guard and a police officer for the first time will be assigned to each of the five high schools. Some middle schools also will be assigned police officers and outfitted with surveillance cameras, an increasingly popular option in the never-ending struggle to keep public schools safe.

The opening of the school year is no longer solely about new teachers, textbooks, classmates and academic programs. In the aftermath of Columbine and grisly school shootings in Paducah, Ky.; Jonesboro, Ark.; and Springfield, Ore., the start of school is also a time to try out new security policies and safety measures.

School districts in the Washington area and nationwide are setting up anonymous telephone hot lines to report trouble, buying new alarms, cameras and metal detectors by the truckload and creating conflict mediation programs to identify potentially dangerous students.

Alexandria has purchased new cellular phones that double as walkie-talkies for all principals. Fairfax County is distributing a new crisis response manual. Montgomery County will spend $685,000 to install surveillance cameras in its 23 high schools, and Prince George's County is supplementing cameras already inside high schools with new ones to monitor school entrances and grounds.

"We have to take some dramatic steps," said Pam Riley, a former school principal who directs the Center for the Prevention of School Violence in Raleigh, N.C. "The public expects when they drop their children off in the morning that they will be safe."

Riley's center is booked through December with appointments to consult with 35 to 40 school districts. It has received more than 5,000 requests for advice since April, when two Columbine students fatally shot 12 classmates and a teacher and then killed themselves.

Last month, Riley met with Maryland Lt. Gov. Kathleen Kennedy Townsend (D) and proposed a host of new security measures, many of which were approved yesterday by the Maryland State Board of Education. They include requiring schools and districts to report each incident of student violence to Annapolis and develop crisis response plans that state officials will review each year.

Maryland also will set up a toll-free hot line to collect tips about guns in schools and other safety concerns and will place mental health experts in four schools -- none in the Washington suburbs -- to identify students who might need counseling or psychiatric care.

"We need to strike the right balance between responsible precautions and paranoia," Townsend said. "Students should be looking at their books, not over their shoulders."

District schools will spend about $2 million on new security measures this year, expanding the number of secondary schools with closed-circuit surveillance cameras from 14 to 29, making digital photo identification cards for all high school students and installing video-linked intercom entry systems in every elementary school.

The entry systems will free up the security officer assigned to each elementary school to patrol halls and respond to fights, thefts and other incidents. Similar setups are in use in some schools in Pittsburgh and New Jersey, said D.C. school security director Patrick Fiel, and could have prevented a shooting rampage this month when a gunman walked into a Jewish community center in Los Angeles and wounded five people, including several children.

Yvonne Morse, the principal at Birney, said parents welcomed the new system when it was tested at her school during the summer session.

"They're real pleased to add another safety factor," said Morse, who takes turns with her office staff checking out visitors on the video monitor. "If we don't know the people, we don't open the door. I feel safer, and I think the kids do, too."

Fiel said the systems are relatively inexpensive -- it will cost about $500,000 to outfit all 104 elementary schools by Christmas -- and tamper-proof. When some Birney youngsters repeatedly rang the door buzzer, Morse identified them on her video screen and spoke to them on the intercom.

"I said, `Let me call your mother, John,' " Morse said. " `I'm going to tell your mother you're playing with the buzzer system.' That was it. One day and it was through."

Fiel and other school officials in the region said they have focused on security for years and emphasized that most of their new initiatives were proposed long before the Columbine shootings. But the tragedy nevertheless has had a grimly visible impact.

Loudoun officials quickly approved the requests for high school security guards in the weeks after the shooting -- even though they had cut the proposal from the previous year's budget.

And because police had trouble navigating Columbine's halls, officials in Montgomery are making sure they have up-to-date blueprints. Alexandria educators are compiling a complete photographic record of the interior of every school.

In exercises at five Montgomery high schools last month, police were told to act immediately in a crisis rather than wait for special tactics officers, which their counterparts did at Columbine.

"They're trained to come in now, guns blazing," Montgomery school spokesman Brian Porter said. "They don't wait."

The details of today's staged rescue mission in Anne Arundel will be kept secret until the exercise begins. Reporters are being invited to ask mock questions as officials evacuate students participating in the exercise and deal with panic-stricken parents who also volunteered for the exercise.

Huntley J. Cross, special assistant for student discipline in Anne Arundel, said he had mixed emotions about the new climate of preparedness.

"This is something that's almost foreign to an educator," said Cross, who has worked in schools for 36 years. "This is something we need to do, but in my wildest imagination I never would have perceived that we'd have to do."

Despite increasing public worries about safety, some school systems have hesitated to adopt the most extreme measures, citing concerns about making school seem less inviting or violating student freedoms.

Although many school systems are eliminating locker visits between classes or requiring see-through backpacks so students cannot hide weapons, a senior Loudoun administrator said he opposed such a proposal.

"We don't force adults to walk around with see-through briefcases," said Terrence W. Hill, Loudoun's director of secondary school instruction.

Those who deal with school safety said technology is far from the only answer -- that frequent communication between students, staff members and parents is considerably more important than metal detectors and other gizmos in identifying the potential for violence.

Riley and others praised initiatives that bring parents into schools. One example is the year-old greeter program at Woodbridge Middle School, in which parent volunteers are stationed at the front door to welcome visitors and direct them to the office.

"It has seemed to help," said Ken Ikeda, a parent. Ikeda said he thinks his school is safe -- but suspects parents at Columbine thought the same. "I guess the tragic thing is, you can't really see things coming."

Staff writers Amy Argetsinger, Victoria Benning, Jay Mathews, David Nakamura, Linda Perlstein, Christina A. Samuels, Brigid Schulte and Liz Seymour contributed to this report.