HAZLE TWP., Pa. -

Nearly 50 people were injured when a tractor trailer slammed into a bus full of children.

It happened just before 11 a.m. Friday on Interstate 81, just north of the border between Schuylkill and Luzerne counties, in Hazle Twp., Luzerne Co.

The students, from the Hazleton YMCA, were on a swimming trip to Pottsville when their bus encountered traffic on I-81 South.

"As that occurred, the school bus began to slow and the operator of a tractor trailer who was following that school bus, one of the two school buses, struck the rear end of that vehicle," said Capt. Edward Hoke, Pa. State Police.

"Your heart kind of stops and you say a quick prayer that everyone is okay, and then you go and do what you need to do," added Sue Farley, president and CEO of the Hazelton YMCA/YWCA.

Workers at the YMCA said the ages of the children ranged from six to 14. The younger kids were on the bus involved in the accident. Forty-seven were injured, including student and counselors.

"Some of the injuries were minor, and those patients have already been discharged with their parents or legal guardians," said James Edwards, president/CEO for Hazelton General Hospital.

"Others are still receiving treatment and will be admitted or discharged, something that will be determined in the normal course of care," Edwards said.

"Initially, when I got there, they were upset and shaken," added Farley. "But when they got here, the hospital staff was so good with them and kind of distracted them. So the kids are doing pretty well."

One counselor was flown to Lehigh Valley Hospital near Allentown.

"From what I understand at this point, her condition has been upgraded and they believe she is going to be okay," said Hoke.

State police said the accident is still being investigated and so far, no citations have been issued to any drivers involved.