After the wounded teacher was hoisted on a gurney and rolled out of Thomas Stone High School, and after the spent shotgun shells in the hallway were cleaned up and the gunman hauled away in cuffs, it was time for refreshments.

"I hope everyone saw the value of this," said Keith Grier, director of student services for the Charles County public schools. He was addressing law enforcement officials and school administrators in the school's cafeteria Wednesday. "We have to be ready for a real Code Red."

A real Code Red is something everybody at the school agreed they hope never to see. Nevertheless, Wednesday's drill was designed to familiarize school personnel and emergency responders with how to react to a crisis involving numerous casualties.

This is the first year that the school district is formally requiring annual lockdown drills at every public school in Charles County, Grier said. The exercises are designed to test the school's emergency response plan and security procedures.

The drill at Thomas Stone in Waldorf is one of many similar exercises officials expect to conduct at different locations in the county over the school year. The operation was funded by the Maryland Emergency Management Agency. Future drills will address various types of emergency situations.

Wednesday's exercise simulated a scenario in which a parking lot dumpster fire is followed by shooting inside the school, with several students and teachers wounded.

The drill was motivated, in part, Grier said, by the 1999 Columbine High School shooting in Jefferson County, Colo., in which two gun-wielding students killed 13 people, as well as the siege at a Russian school last month in which a firestorm of explosions and shooting by terrorists killed hundreds of children and adults.

The drill was primarily designed to see how several agencies work together in a sudden crisis. It was also meant to be a "learning experience, not a test," its organizers said.

"The police department knows what to do, and the fire department knows what to do, and the school administrators know what to do, but this drill gets all these agencies together so that all the responses are coordinated," Grier said.

The two-hour-long drill began about 1:30 p.m. with a briefing in the library of the school. Students had been dismissed early for the day as part of the school's regular calendar. Nearly 30 student volunteers -- most from Thomas Stone -- participated as "victim" actors.

The planned pandemonium got underway when a parking lot dumpster was set ablaze. As observers -- principals and vice principals from throughout the county -- stood behind yellow police tape inside the school, many wearing ear plugs, the sounds of shots could be heard coming from a classroom.

"What about the students?" asked Thomas Stone High School Vice Principal Jan Johnson over her radio, assessing the situation from outside the school. Soon, two bloodied students came running out of the school, followed by a few others.

More deafening shots are heard in the school's hallway, and four Charles County sheriff's officers soon make their way into the school's J-wing, guns drawn. Three more students trying to escape from the building dart in front of the officers.

Eventually, after one of the school's teachers and Principal Heath Morrison are found shot inside the school, police shoot one of the mock intruders and arrest the other.

"This was a great learning experience of how well prepared we are, and I was very impressed," Grier said in the cafeteria during a evaluation session after the drill.

He said one area that could be improved is communication among the 13 participating agencies, including the sheriff's offices from Charles and St. Mary's counties, the Maryland State Police, the Charles and St. Mary's county public schools and several rescue squads.

"I think we could use more effective communications," Grier said. "We were, at one time, using three different radio frequencies. It would be better if we could use just one."

Grier stressed the importance of such drills.

"These are very important learning tools," Grier said. "Our school system has a goal to be as safe as any school in the state of Maryland. This can't take a back seat to anything."

Charles County Sheriff Fred Davis (R) said the drill also was a precursor to a larger, multi-agency disaster drill scheduled for January at the St. Charles Towne Center shopping mall.

"It is unfortunate that we have to have to be involved in intensive exercises and drills that prepare our personnel to handle worst-case scenarios," Davis said. "But, given this day and age, I believe that it is necessary and essential that we practice and plan with the idea of planning for the worst and hoping for the best."

For the emergency preparedness drill, a shooting was staged inside Thomas Stone High School. Student actors Robbie Jackson, left, and Emily Myers run after being freed by responding police.Pfc. Dorrell Savoy of the Charles County Sheriff's Office works his way down a school hallway during the emergency preparedness drill.