Airline flight crews were also grounded by the mysterious smell.
A hazmat team was called to the Coast Gateway hotel just after 12:30 after several people had complaints of a strong odor and respiratory problems on the fourth floor. Six ambulances arrived to help deal with the sickened guests, which included visitors, employees and a number of Sea-Tac Airport flight crews.
"I was going down the hallway and I could smell something that started to irritate me and my throat," said hotel guest Russ Derler.
Of the 17 people who complained of breathing problems, 13 were taken to the hospital to be checked out.. Hazmat teams brought in large fans to ventilate the area.
Several crews of pilots and flight attendants were staying at the hotel and were impacted by the smell. The flight crews and the fire department say the airlines are overly cautious when it comes to the health of their teams. They don't want anyone flying who may have breathing issues, no matter how minor.
"I started coughing as I was getting dressed and when I got in the hallway it was really bad. I started coughing," said Delta pilot Oren Cohen.
Police say they are checking into the possibility the smell could be pepper spray used during an argument on the 4th floor, but hazmat teams couldn't find the source and guests were being allowed back in around 2:30 p.m.