A Pennsylvania state police trooper was shot in the shoulder after a routine traffic stop evolved into a high-speed chase Tuesday, ending with a fiery crash on a Philadelphia highway.

The incident began at around 9:30 a.m. on I-76 at University Avenue when Pennsylvania State Troopers stopped a car for expired registration, according to ABC's Pennsylvania affiliate WPVI-TV.

Police report that there were four men inside the car who exited the car after they were stopped. One of the men was handcuffed, while another man, the alleged gunman, suddenly re-entered the vehicle and drove off.

Troopers pursued the man, leaving the three unattended, leading to a high-speed chase along I-676, which runs through the center of Philadelphia.

Trooper Patrick R. Casey, who was providing backup, got in front of the suspect in an attempt to conduct an induced stop, but he was instead rammed by the suspect, who rode alongside him and started to open fire, according to ABC News.

The suspect then crashed into a school bus, causing both vehicles to burst into flames. The suspect then exited the vehicle and began firing upon Casey once more.

At some point during the chase, Casey, 31, was hit in the shoulder by gunfire, forcing him to be taken to the hospital in stable condition.

State police say that the suspected gunman and two others are in custody, reported the Associated Press. The first suspect was identified as 17-year-old Giovanni Cotto, who has been charged as an adult on three counts of Criminal Attempt to Murder of the 1st Degree, three counts of Aggravated Assault, three counts of Assault of Law Enforcement Officer, three counts of Simple Assault, Fleeing and Attempting to Elude, Recklessly Endangering Another Person, Possessing Instruments of Crime, and several Firearms Act Violations.

The second suspect, who remains unnamed and is believed to be in his 20s, gave police a fake name when the Cotto drove off.

The stretch of road where the crash took place was closed in both directions, but it reopened later in the day.

No other information was immediately available.