CARSON CITY, Nev. (AP) — Before the breakfast-time massacre killed three National Guard members and sent tremors of fear through Nevada’s state capital, Sgt. 1st Class Miranda McElhiney drew a happy face on a poster board outside her office door and wrote her last message to the world: “staff meeting. Will return by 11:00.”

She never returned. What should have been a routine gathering over pancakes and eggs at an IHOP Tuesday morning ended in panic, terror and death when a gunman burst into the Carson City restaurant and released a blaze of bullets that struck every uniformed Guard member in the dining room. A patron was also killed before the attacker fatally shot himself in the head.

Among the four people killed by the gunman in the still-unexplained shooting was an Iraq War veteran who loved military history, a Navy crewman who had served in Afghanistan and a devoted grandmother who crocheted blankets for every pregnant woman in her life.

“This is unquestionably the most devastating attack in Carson City’s history,” Sheriff Kenny Furlong said on Wednesday. “Yesterday our town was shocked to the core.”

Exactly what set the gunman, 32-year-old Eduardo Sencion, off  remained unclear. Family members told police that Sencion was mentally troubled, but he did not have a criminal history.