The school bus comes to a sudden stop. Quickly, a safety patrol member inside opens the emergency door at the rear of the bus, and one by one, 36 students jump to the ground and run to safety.

The evacuation is over in 40 seconds.

The situation is not a real emergency, however, and the students are not on their way to school.

They are members of safety patrol squads from a number of Prince George's County elementary schools who are performing one of many drills they learn at a weeklong safety patrol camp at Croom Vocational High School.

The camp, run for 32 years by the Prince George's County Police Department in conjunction with the school system, is designed to train elementary school students as safety patrol officers -- sergeants, lieutenants and captains.

Besides learning what to do in a bus emergency -- how to open the emergency door, for instance, or use a fire extinguisher or emergency brake -- patrols also are trained in more mundane matters: how to take children safely across the street, how to help students get on and off a bus and how to use power over their fellow students wisely, earning their respect.

"We train the officers, and then they go back to their own schools and tell their patrols how to do it," said Cpl. Patrick Grogan, the camp director.

The camp has five sessions per summer, with about 100 students participating each week, Grogan said. Each of the county's 114 elementary schools can send four students, two boys and two girls, usually those students who the school's patrol sponsor thinks would make good officers.

Officers coordinate the patrol squad, said Grogan. Their duties include presiding at meetings, checking daily to see that posts are filled and making reports of any unusual or dangerous incidents. They are usually sixth graders, while regular patrol members can be either fifth or sixth graders.

Regina Nash, who will be a sixth grader at John E. Howard Elementary School in Capitol Heights in September, said she hopes the training will qualify her to become a captain. Regina, 11, was a crossing guard last year. She said she liked the bus evacuation drill the best. "I never worked on a bus before," she said. "Now I know what to do."

Students spend their mornings in class, studying the safety patrol officer's training manual, Grogan said, and their afternoons at play, swimming, roller skating or playing softball. "We try to teach them leadership and responsibility, but we also want them to have fun," he said.

Amir Boyd, 10, a sergeant at Shadyside Elementary School in Suitland, said that much to his surprise, he did have fun. "I thought it was going to be boring, but I like it a lot."

The camp fee is $45 a week and is usually paid by the school's PTA, although sometimes students must pay themselves.

To "graduate" from the camp, students must pass a 40-question multiple choice exam given at the end of the week, said Grogan, as well as a "field exam," in which students perform various patrol duties at nearby Marlton Elementary School.

"You can't just learn it in a book. You have to be able to do it in real situations," said Grogan.

One patrol member recently showed how well he could perform in a real emergency. Quinn Brunson, a sixth grader at Owens Road Elementary School in Oxon Hill, used his patrol training to save a student's life.

Last April, as a kindergarten student was crossing Kennebec Street in Oxon Hill to board a school bus, a car sped toward her, ignoring the bus' flashing red lights. As the bus driver frantically honked the horn, Quinn, on bus patrol duty, ran into the path of the oncoming car and pulled the girl to safety.

Quinn, now 12, was named Patrol of the Year in Maryland for his heroic effort. He received a certificate from County Executive Parris Glendening at the camp last week. Still, he protested, "It was no big deal."