SALT LAKE CITY -- Ten people were hospitalized and dozens of others sickened after a hazardous materials incident at Temple Square.
It happened Thursday morning at The Church of Jesus Christ of Latter-day Saints' South Visitors Center.
"It just started slightly and then got stronger and stronger," said Susan Lowe, an LDS missionary in the visitors center. "Little scratchy throat, then the alarm went off."
Salt Lake City firefighters said a chemical cloud moved through the ventilation system, sickening about 50 people.
"A strong smell came out of the air vents," said David Gillette, the LDS Mission President for Temple Square. "It did smell to me like chlorine. So we went around trying to find the source, if there was a spill or something, and then all of a sudden the alarm went off."
Someone had pulled the fire alarm and dozens of people evacuated. Salt Lake City police and firefighters shut down South Temple from Main Street to West Temple, including halting TRAX service. Half of Temple Square was also evacuated, said fire department spokesman Jasen Asay.
Firefighters said a janitor poured chlorine into an empty container that still had remnants of sulfuric acid still inside. The remnant of the acid and the chlorine mixed to create thionyl chloride.
Thionyl chloride is described as a sometimes colorless, fuming liquid with a suffocating odor. In some cases, it can be lethal.
"These ten people have had symptoms of coughing, some burning and a little bit of nausea," said Asay. "The worker, the janitor who combined the chemicals was one of the ten. He had the worst symptoms but they were all transported in minor condition."
After about an hour, Temple Square and surrounding streets were re-opened.