The suspect is an Army veteran, with one deployment to Iraq in 2007-8. According to his wife, who filed for a protective order, he is suffering from PTSD, has an arsenal of guns and has threatened suicide. He is also a suspect in the shooting of four people in south Seattle seven hours prior to shooting the ranger.
This all started when the suspect blew past a checkpoint to check that you have tire chains for the snowy roads. Ms. Anderson, one of the Park's 15 LEO rangers, set up a roadblock and was shot through the windshield with a shotgun before she had exited her vehicle. The suspect then fled on foot and was firing at backup vehicles responding to the scene.
PS: Here is a photo of the suspect published in this morning's Seattle Times: