The “fire” that shut down the Beacon Hill station tunnel on Monday evening was actually smoke from a fire set outside the tunnel by homeless campers, reports the Seattle Times.

The smoke, which smelled like burnt plastic or something electrical, shut down rail service for almost two hours. One Beacon Hill neighbor told us: “We drove past the station just before 8 p.m. There were bunches of fire trucks, etc. with the whole station blocked off. I checked 911 online when I got home and found the mention of the 6:30 (give or take) calls categorized as ‘tunnel fire’ and saw that they appeared to have dispatched everybody.”

No smoke alarms tripped in the tunnel, and full service started again by 8 p.m.