NEW: A state police trooper says at least one person was killed in the crash
Helicopters transport six injured students to hospitals, a 911 dispatcher says
Two other buses take 22 students with less serious injuries to a hospital, she says
More than two dozen students were injured and at least one person was killed when a packed school bus collided with a semi-trailer truck in southern Pennsylvania on Wednesday, officials said.
At least one person was killed in the crash, Pennsylvania State Police Trooper Scott Kovach said.
Medical helicopters were transporting six students to hospitals, said Geraldine Budzina, a dispatcher with Somerset County 911.
Two other school buses were taking 22 students with less serious injuries to a hospital, she said.
As many as 70 students may have been on the school bus, she said.