A gunman murdered a woman decorating a tiny church hall for a children's Christmas party and killed two men elsewhere in a rural township before being shot dead in a gun battle with state troopers.

Three troopers in patrol cars were injured in a pursuit that began after the gunman, driving a pick-up truck, fired at them, police said.

One trooper injured a wrist and was then hit in the chest but was saved by his bulletproof vest.

The gunman was killed during a final exchange of gunfire after ramming his truck head-on into another police cruiser, authorities said.

The shootings began in Frankstown Township, in central Pennsylvania, US, at about 9am yesterday, and investigators were processing five crime scenes within about a 1.5-mile radius.

Troopers were responding to an emergency services call of a shooting in the township when they heard calls reporting at least one other shooting elsewhere, state police said.

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

Authorities did not release the names of the victims or the gunman, but said the man lived in Blair County.

State police said they were still trying to piece together a timeline and motive. The gunman and the victims were not related, though the victims may have been, at least distantly, Blair County district attorney Rich Consiglio said.

Besides the woman, Lt Col Bivens said, one man was shot at a residence, and the other man was shot at a crash site where the gunman "used his truck and also struck that vehicle much in the same manner that he did to our state police officer".

But family members of the victims said they were told the woman at the church was the first person shot, the Pittsburgh Tribune-Review said. The gunman then shot two men in the driveway of a home after a confrontation at a stop sign, one of the men's cousins, Marie Brenneman, told the paper.

"This person went to their driveway with a pistol, pointed at them and started shooting," Ms Brenneman said.

She said both men were the gunman's neighbours in the tiny village of Geeseytown, about 70 miles west of Harrisburg, the state capital.

"They were uneasy around him," she said.

The woman at Juniata Valley Gospel Church had cooked food the day before for the funeral of the church's long-time pastor, said the Rev James McCaulley, his brother.

The church was still reeling from the Rev David McCaulley's death when the woman returned to decorate its hall - named after the pastor of 58 years - and bullets ripped through a window, he said.

The gunman then entered and shot one of two women before he left, the minister said.

Police identified the five crime scenes as the church; a home and ground around the home; a crash site where another victim was killed; the point in the road where the gunman opened fire on the troopers; and where the final encounter occurred after the truck collided with the police cruiser.

Lt Col Bivens said investigators did not know if the victims were picked at random.

Besides the trooper wounded twice, a second trooper was injured by glass fragments in his eye and bullet fragments that hit him in the forehead, Lt Col Bivens said. The third trooper suffered minor injuries from the head-on crash.

"I think we have three very fortunate state police members tonight," he said. "We are very thankful for the fact that they survived this attack. Someone was watching over them."

Mr McCaulley, the pastor of another church about 50 miles away from the site of yesterday's carnage, said his older brother began leading the Frankstown church in 1954.

"He preached his last sermon at the church in October before he fell ill," McCaulley said.

The church, which lists about 150 members in an online advert posted this month for an associate pastor, is close-knit, and the woman killed yesterday was among its more active members, Mr McCaulley said. She had made food for him to take home on Thursday since his wife had died this year, he said.

Yesterday's shootings were the second involving a rural Pennsylvania church this month. An elementary school teacher is in jail accused of shooting dead his ex-wife, a church organist, during a service in Coudersport on December 2.

The pastor and church members subdued him until police arrived.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.