Four people died on a rural Pennsylvania highway Friday when a gunman killed three people and later died in a shootout with police, authorities said. Three state troopers were injured, one of whom was saved from worse wounds by the bulletproof vest he wore.

The incident comes as the nation remained on edge a week after a gunman invaded a western Connecticut elementary school, killing 20 children and six adults before committing suicide in the building.

It also comes as gun control remains a major topic on the political agenda with the Obama administration and some Democrats seeking to craft tougher federal proposals while the National Rifle Assn., the lobbying group, vowed it would continue to fight new restrictions and insisted the better path was to increase armed security.

“The only thing that stops a bad guy with a gun is a good guy with a gun,” NRA chief Wayne LaPierre said at a televised Washington news conference.

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