The police were trying to figure out the motive of a gunman who killed three people before being shot dead by state troopers in rural Pennsylvania on Friday.

"We don't believe it was a domestic dispute, but we also don't know a motive, because the shooter was not related to any of the victims," David McGarvey, a state police spokesman, said hours after the incident, according to Reuters.

The police were trying to piece together a timeline of events that occurred in a 1.5-mile radius and involved five crime scenes in Frankstown Township in Blair County, the Associated Press reported.

"It's going to take us some time to put this all together ... and know exactly what occurred," said Lt. Col. George Bivens, a deputy state police commissioner.

There were also contradicting reports regarding the sequence of events. Quoting the relatives of the victims, the Pittsburgh Tribune-Review reported that the gunman shot the woman first and then shot two men in the driveway of a home.

“Besides the woman, one man was shot at a home and the other man was shot at a crash site where the gunman had used his truck to strike another vehicle,” Bivens told the AP.

A Reuters report said that the rampage in Pennsylvania began as the gunman shot dead a woman, who was decorating a Christmas tree inside a church for a children’s party. He then shot dead two men in their respective homes before being killed by police while he was trying to flee in a pickup truck.

All the three incidents happened a short distance from one another, and three troopers who were involved in the shootout with the gunman were injured in the incident, according to Reuters.  

The police were yet to reveal the identity of the victims and that of the gunman. However, quoting the victims’ relatives, the AP reported that the two dead men were the shooter's neighbors in the tiny village of Geeseytown, about 70 miles west of Harrisburg.

The gunman exchanged fire with the troopers, who had rushed to the crime scene, and two of them got injured while another trooper was hut after the gunman rammed his car head-on to with the police vehicle. The gunman was shot dead at the crash site.

All the three injured troopers were treated at a local hospital and discharged later.

The incident happened a week after the Newtown massacre in Connecticut, in which 20-year-old Adam Lanza shot dead his mother and 26 others at a school, triggering a debate on the gun control laws in the country.

In a statement Friday, the National Rifle Association -- a pro-gun lobby that has come under fire following the killings -- urged the government to appoint armed guards in schools to enhance security.