The deceased ranger was identified as 34-year-old Margaret Anderson. She was a mother of two.
Pierce County Sheriff's spokesman Ed Troyer said late Sunday afternoon Benjamin Colton Barnes, a 24-year-old believed to have survivalist skills, was a "strong person of interest" in the slaying of Margaret Anderson.
Barnes was also a suspect in a shooting that left four wounded in Skyway, Wash., earlier Sunday.
Authorities said the shooting happened just before 11 a.m. near the Longmire Ranger Station in the southwestern part of the 368-square-mile park in Washington state.
Police say Barnes blew through a checkpoint at the park yesterday morning.
When Anderson tried to stop him at a road block, police say Barnes shot and killed her, and then fled into the wilderness.
According to Troyer, shots were still being fired within park boundaries just after noon.
The patrol and the sheriff's office were working together to find a man carrying a long rifle. Authorities closed the park as they searched for the suspect.
According to ABC News, Barnes' car was found abandoned, equipped with weapons and body armor. He's believed to have military experience and possess skills to survive in the wild.
Earlier in the day, Barnes was reportedly asked to leave following a dispute at a party and returned later and started shooting. Two of those victims were in critical condition.
The Associated Press contributed ot this report.