It all began shortly before 5 a.m. Wednesday on Route 22 between the intersection of Route 309 and Cedar Crest Boulevard.
Police say the gunman, 45-year-old Za Uk Lian of South Whitehall Township, was behind the wheel of a white Toyota Camry when he had some kind of encounter with another vehicle on Route 22.
The District Attorney's Office said Lian fired a shot at the other vehicle.
Police said the female driver of that vehicle was not injured and was not aware her vehicle had been fired upon.
The woman drove to the Wawa convenience store at Route 100 and Schantz Road to get a sandwich. When she came out of the store, she noticed there was a bullet hole in her car.
Police said the woman told officers she did remember hearing a loud bang.
Meanwhile, police said Lian also pulled into the same Wawa parking lot, seemingly by coincidence.
Investigators say he fired at a Jeep and struck the driver. Police said the driver of the Jeep was receiving treatment for injuries that do not appear to be life-threatening.
Then, in the same parking lot, Lian shot a truck driver who was pumping gas into his vehicle, District Attorney Jim Martin said.
That victim, 31-year-old Ramon Ramirez of Allentown, died of his injuries, police said.
Family members described Ramirez as a devoted father of three who was known for his strong work ethic.
Following that fatal shooting, investigators say Lian ran south on Route 100 and ended up near the Brookside Children's Education Center where investigators say he took his own life.
Authorities were trying to determine a motive, and Martin said the preliminary investigation indicated the shootings were "indiscriminate" and unrelated.
The shootings drew a large police presence. Nearby businesses and a school closed.
According to authorities, an employee of the Wawa was taking out the trash when he heard the gunshots. He ushered customers from the parking lot into the Wawa, alerted his coworkers to shelter in place and locked the doors.
Trooper Nathan Branosky of the Pennsylvania State Police Troop M said a trooper involved in traffic control was struck by a vehicle. He was taken to the hospital where he was treated and released.
This story has been updated to show the suspect's vehicle was a Toyota Camry not Corolla as first reported by authorities