"Emergency crews are responding to Coast Guard Base Seattle after 2 Coast Guard members were exposed to an unknown white substance while handling mail," the Coast Guard said in a Twitter message.
A spokesperson for the Pacific Northwest Coast Guard told KOMO News that the workers have not shown any signs of injuries or illness, but are being quarantined.
Meanwhile, the suspicious white substance found while Coast Guard members were working with the mail at a base in Seattle was not hazardous, the city's Fire Department said in a statement on Monday.
"Seattle Fire Haz Mat team determined no hazard associated with the mysterious white powder found coming from a package at USCG [United States Coast Guard]," the fire department said in a Twitter message.
