Austin firefighters responding to a hazardous materials call found a man thought to be in his 20s dead in anapartment Wednesday afternoon. It was unclear if the victim is a University of Texas student, firefighters said.

Paramedics took two people to University Medical Center Brackenridge in connection with the incident at 21 Pearl Apartments in West Campus near 21st and Pearl streets. Three others were treated at the scene, Austin Fire Division Chief Palmer Buck said.

Firefighters responded to the hazardous materials call at about 3:22 p.m. They found the man in cardiac arrest and attempted to resuscitate him, Buck said. Firefighters also found indications of hydrogen sulfide inside the apartment.

Buck said the first firefighters found a “warning sign” outside of the victim’s apartment but Buck did not elaborate further.

The manner and cause of death of the man will be determined by the Travis County medical examiner’s office.

Residents of the apartment building, mostly UT students, have remained outside of the building for about an hour.

At 4:30 p.m., Pearl Street remained closed from 21st to 23rd streets, officials said.