The incident began at 1:45 p.m. when the former employee entered the Hillel center and made threats to workers and his former bosses in the building, said Det. Mark Jamieson with Seattle police.
"Then he went immediately down into the basement and began mixing some cleaning chemicals," Jamieson said.
One of the employees followed him down into the basement and saw what he was doing. That employee got everyone out of the building and called 911.
When Seattle police officers and firefighters arrived, they could see the man had been overcome by fumes. Officers were eventually able to get the man to willingly come out and get hosed off by firefighters.
The man was then taken to a local hospital for treatment of inhaling toxic fumes.
Police blocked off the area around NE 50th Street and 17th Ave. NE for about two hours so the bomb squad could sweep the building for any explosives and HazMat officials could ventilate the building.
No one else was injured.