PARK RANGER MARGARET ANDERSON was operating a roadblock in Mount Rainier National Park on New Year’s Day to prevent cars without snow chains from proceeding up the mountain. What should have been a routine assignment turned deadly, authorities say, when Benjamin Colton Barnes tried to evade a stop by shooting repeatedly into the side of Ms. Anderson’s patrol car. The barrage killed the 34-year-old mother of two little girls.

This was not the first violent incident of the day involving Mr. Barnes, officials said. In the first few hours of 2012, Mr. Barnes and a group of friends were playing “show and tell” with their guns when a fight broke out and Mr. Barnes and another individual are believed to have shot four people. Mr. Barnes then traveled to Mount Rainier to hide from authorities. After shooting the park ranger, Mr. Barnes escaped into the woods; he was found hours later frozen to death, wearing only a T-shirt and jeans, with a knife, ammunition and at least two firearms, including an assault-style weapon.

Mr. Barnes apparently was an emotionally plagued young man. He served a tour of duty in Iraq in 2007 but was discharged from the military some two years later after a drunk driving incident and improper transport of a private weapon, according to The Seattle Times. An ex-girlfriend, with whom he has an infant daughter, filed for a restraining order over the summer after describing Mr. Barnes as erratic and possibly suffering from post-traumatic stress disorder. She noted that Mr. Barnes owned a small arsenal. One photograph released by Washington state law enforcement officials show a bare-chested Mr. Barnes brandishing two assault-style weapons. Did officials follow-up on the ex-girlfriend’s complaint or ask whether someone as apparently unstable as Mr. Barnes should be permitted to own and keep guns?

It is unclear when and how Mr. Barnes obtained the weapons, but it probably was not difficult to do so. Washington has among the most lax gun laws in the country, requiring neither training nor permits before a purchase. The state does not compel registration and allows individuals without a serious criminal record or history of mental illness to obtain permits to carry a concealed weapon.

There is no way to know whether tougher gun restrictions would have prevented Mr. Barnes from obtaining his weapons. But it is beyond dispute that easy access to firearms can quickly turn a simple argument or difficult situation into a deadly confrontation. And this violence is not limited to the proverbial mean streets. That terrible lesson was again imparted on New Year’s Day when the life of a young woman was cut short in one of the country’s most tranquil and majestic sites.