Three firefighters responding to a call Tuesday about what was described as a respiratory irritant in a Seattle apartment building were later taken to a hospital with five others after experiencing symptoms related to the substance.

The Seattle Fire Department responded to 911 calls at about 12:45 p.m. about an unknown odor causing respiratory issues in a south Seattle seven-story apartment building, the department said in a blog post.

Firefighters encountered residents on the third floor experiencing symptoms related to the unknown substance. Ten people were treated at the scene for related injuries, the post said.
3 BALTIMORE FIREFIGHTER DEATHS BEING INVESTIGATED AS HOMICIDES

Eight of them were taken to a hospital while the other two declined further medical care. One person, a 54-year-old woman, was transported to the hospital in serious condition. The three firefighters were all in stable condition and were taken to the hospital for further evaluation, fire officials said.

Firefighters ventilated the area to remove the substance. Hazmat crews confirmed the substance was an airborne respiratory irritant, but officials did not specifically say what it was.

They ventilated the building until about 4 p.m. when monitoring equipment deemed it safe for residents to return, fire officials said.