Twenty-one Prince George's County students suffered minor injuries yesterday morning in Brandywine when a school bus that had stopped to pick up students was struck by another bus on the way to school.

The injured students, who complained of neck, back or stomach pains, were taken to Southern Maryland Hospital Center in Clinton, where they were treated and released, said Lt. Mark Brady, spokesman for the Prince George's Fire Department.

"All of them are what I would consider minor injuries," Brady said.

The accident occurred during the county's second week of school as parents and students are still getting used to new bus routes and pickup times. There have been some missed routes and other confusion--as is typical in any school year--and transportation officials have been trying to iron out the kinks.

Meanwhile, like most Washington area school districts, Prince George's is struggling to recruit enough bus drivers and substitute drivers. Superintendent Iris T. Metts said yesterday that she wants the system to make a more concerted effort to hire drivers throughout the year, just as they have begun to intensify their teacher hiring efforts.

According to police and school officials, the accident occurred about 7:30 a.m. when a school bus that was stopped on Lusby Lane near Heatherwick Drive was struck from behind by the second bus. Both buses had been en route to Gwynn Park Middle School and Gwynn Park High.

"We're not sure if it was inattentiveness or what on the part of the second driver," said Prince George's police Lt. Andy Ellis.

About 40 to 45 students were on each bus, less than the capacity of about 50 to 58, said Tony Leibatore, who oversees transportation for the school system. Under system rules, school buses cannot exceed 45 mph on any road and students are required to remain seated while the bus is moving.

Police said yesterday that neither driver had been charged.

The female driver of the trailing bus, school officials said, has been driving buses full time for the district since 1996. Leibatore said that she has been suspended for 48 hours pending the results of a drug and alcohol test, which is routine procedure. That driver also will be required to explain her actions before an accident review committee, which will determine her role in the incident.

The driver of the lead bus was a substitute driver who has driven for the system since 1997, he said.

All bus drivers are required under state law to have at least 22 hours of classroom instruction and a minimum of 20 hours of on-road training, Leibatore said, and most Prince George's drivers have as much as 40 hours of on-road experience before being allowed to pick up students. All drivers also must attend monthly safety meetings.

"My main concern was, were there serious injuries? No," Leibatore said. "It was a minor accident. The first bus lost a taillight and had a dent in the bumper."

Both buses were taken away for repairs. Students were removed from the buses and taken to their schools by other buses.

Usually, buses in the county make three trips in the morning--to a high school, a middle school and an elementary school--and three in the afternoon. In this case, both buses were running combined routes to Gwynn Park Middle School and Gwynn Park High, which open at 7:55 a.m. and 8 a.m., respectively.

Leibatore said there are no plans to change the routes.

Metts called the accident "embarrassing" and said she was still trying to figure out how it happened.

"I'm sure we're trying to get to the bottom of it," she said. "It does seem incredible that you didn't see a yellow bus in front of you."