SALT LAKE CITY — Two chemicals were accidentally mixed together at Temple Square on Thursday, creating a hazardous materials scare that resulted in 10 people being sent to the hospital.

About 11:30 a.m., a janitor inside Temple Square's South Visitors' Center, 50 W. South Temple, was pouring chlorine into what he thought was an empty bottle, said Salt Lake City Fire Department spokesman Jasen Asay. But there were traces of sulfuric acid inside from a previous job.

The mixture created a vapor cloud of thionyl chloride, he said.

"When you breathe it, it creates burning in the mucus membrane, coughing and nausea," Asay said.

The amount of chemicals mixed was small, but the room was small enough that many people were affected, he said.

About 50 people were evacuated from the visitors center. The south end of Temple Square was also blocked off, and TRAX service between the Gallivan Plaza and Arena stations was stopped because of emergency vehicles on the tracks.

All 50 people were evaluated by firefighters and paramedics. Ten, including the janitor, were sent to local hospitals for further evaluation as a precaution.

The best way to treat people who may have breathed the chemical was to get them fresh air, Asay said. Many of those evacuated showed improvement immediately after getting out of the building.

The building's air system eventually pumped the chemical outside, where it quickly dissipated and did not pose a threat, he said.

TRAX service and the closed roads were reopened a little after 1 p.m.

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