Twelve people exposed to a suspicious chemical odor at a hotel in Palo Alto were hospitalized Thursday night.
Palo Alto fire officials responded to the Westin Hotel on El Camino Real to a report of an odor coming from the hotel's parking garage.
A hazardous materials team was called to the hotel, but investigators were not able to determine the cause of the irritant, according to fire officials.
The scene was cleared shortly after midnight, and fire officials said it appears the irritant was vented out of the garage and had dissipated.
Eight patients were transported to Stanford Medical Center, and four patients were transported to El Camino Hospital for treatment, officials said.
The garage and first floor of the hotel were evacuated, but hotel guests on the third and fourth floors were asked to shelter in place while hazardous materials teams from Palo Alto and Mountain View investigated the incident.
The hotel's HVAC system was turned off to ensure the odor wouldn't travel through the upper floors, fire officials said.
Fire officials first reported the incident Thursday 10:37 p.m.