A 41-year-old man was arrested after attacking a security guard at the Beacon Hill Transit Tunnel early Tuesday, Seattle police said in a blotter post.

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Police said around 3:45 a.m. a security guard, who was checking on a tripped door alarm inside the station, found a suspect inside the employee break room.

The suspect “had donned a Transit Security Jacket and was rummaging through employees’ belongings,” when the security guard found him, police said.

Police said a struggle ensued, as the suspect used the guard’s collapsible baton and struck him in the head.

Arriving officers were greeted by the suspect who was posing as the guard – wearing a Transit Security jacket and holding the baton.

The suspect then held a door open for police and identified the injured guard as an intruder before locking himself in a gated area. Another security guard then unlocked the gated area.

“The suspect ignored officers’ commands to drop the baton and said he was going to kill them, but police eventually convinced the man to drop the baton and took him into custody,” police said.

The guard was transported to Harborview Medical Center for treatment and the 41-year-old suspect was booked into King County Jail.