By Steve Tawa

PHILADELPHIA (CBS) — The Philadelphia teenager who allegedly opened fire on a state trooper on the Vine Street Expressway last November waived his preliminary hearing.

The defendant, already held on $3-million bail, is scheduled to be arraigned next month.

Seventeen-year old Giovanni Cotto acknowledged to prosecutors and the judge that he understood the charges.

Assistant DA Erin Boyle says they may see a plea arrangement, before trial.

“He may wind up pleading guilty.”

Also prosecuting the case, her co-counsel, Tanner Rouse says the teen is carrying over serious charges.

“He’s facing three counts of attempted murder, aggravated assault, and assault on a law enforcement officer.”

Those are just the main charges, along with causing a catastrophe.

During a routine stop for an expired registration on the Schuylkill Expressway, troopers told four occupants to file out. They did, but Cotto jumped back in and sped off. Arriving as backup, Trooper Patrick Casey gave chase.

When they got to the Vine Street Expressway, the trooper pulled alongside Cotto’s car, and the teen allegedly opened fire, before ramming the rear end of an empty school bus, which erupted into flames.

Authorities contend the teen jumped out and continued firing, and the trooper, while shot in the shoulder, returned fire from his cruiser.

Responding troopers and a pair of detectives from the DA’s office who happened to be in another vehicle captured Cotto, after a brief foot pursuit.