Gunman kills 3 in rural US

A MAN armed with a pistol shot and killed three people on Friday in rural western Pennsylvania, one of them in a church, before he was killed in a shootout with state troopers as he tried to flee in a pickup truck, authorities said.

Three state troopers were injured in their confrontation with the gunman in Frankstown, 160km east of Pittsburgh, shortly after 9am, state police said.

The violence in Pennsylvania unfolded as bells tolled and many Americans were observing a moment of silence for the 20 children and six adults shot dead one week ago by a gunman at an elementary school in Newtown, Connecticut.

The Newtown shooter, Adam Lanza, 20, also killed his mother at their home before going on his rampage, which ended with his suicide and has reignited a national debate over gun control.

The National Rifle Association pro-gun lobby is urging that armed guards be placed at schools to improve security.

On Friday evening, investigators were still piecing together events behind the deadly shootings in Pennsylvania.

"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," said state police spokesman David McGarvey.

In fairly rapid succession, the gunman shot and killed a woman inside a church, then fatally shot two men at their respective homes - all within a short distance from each other - before trying to flee in his pickup truck.

He opened fire at two state police patrol cars rushing to the scene as he passed them and slammed head-on into a third patrol car. The gunman was killed in an exchange of gunfire with police at the crash scene, McGarvey said.

The identities of the gunman and his victims were being withheld until their next of kin had been notified, he said.

Another state police spokesman said it did not appear that the shooting had any connection to the tragedy in Connecticut, but added: "That's all still being looked into". -