Firefighters were called out to a county court building in downtown Phoenix Wednesday after white powder was found inside a letter.
Authorities say someone opened the letter on the 4th floor of the building near 3rd Avenue and Jefferson.
Crews cordoned off the area while working to find out who came into contact with the suspicious powder.
"We identified two people that had been exposed. Basically what we do with those people is we wash their hands with hot, soapy water, get that exposure away from them," said Captain Jonathan Jacobs of the Phoenix Fire Department.
"Right now, we don't have a quarantine or anything crazy like that," he added.
Firefighters say a postal inspector is going to examine the substance at a state crime lab to determine whether or not it's harmful.
There's no word on who sent the letter.