Still Not Clear What Caused School Bus To Crash In Baltimore Co.

HEREFORD, Md. (WJZ) -- The investigation continues into a serious school bus accident in northern Baltimore County. Nine children were hurt when the bus flipped onto its side Wednesday.

Some students did not make it to school Thursday following the frightening ordeal. At last check, the bus driver is still in critical condition.

On Thursday, WJZ learned she is 65-year-old Bonnie Pessaro. She was alert for a moment after the crash before being rushed to Sinai Trauma Center with serious injuries.

Sky Eye Chopper 13 was over the dramatic scene. Baltimore County Police released the full 911 call Thursday.

The scene unfolded on York Road, bringing traffic to a halt.

Among the convoy of first responders--a sea of children--shocked, but thankfully, alive. They talked only with WJZ moments after the crash.

WATCH: Shocked Students Recount Baltimore Co. School Bus Crash

"I got kind of blacked out for a second. And when I opened my eyes again, we were on the ground and the bus was tilted over, and I just saw everyone in shock," one student said.

Police say 44 people were on board, including the driver.

"The bus driver got completely cut up. She got in an ambulance," said student Nick Dowell.

Some questions still left to answer -- What caused the crash, and how did the driver end up losing control?

One thing is certain: The bus did exactly what it was designed to do. Experts say despite a lack of seat belts, modern buses are built to protect students in cases of impact.

"It's a testament to the way the bus is built," said Nardos King, with Baltimore County Public Schools.

The crash remains under investigation.