Authorities in hazardous materials suits are searching an apartment in downtown Spokane, Wash., as they investigate the recent discovery of a pair of letters containing the deadly poison ricin.
FBI agents, Spokane police officers and U.S. Postal Inspection Service officials descended on the apartment Saturday morning.
No arrests have been made. An FBI spokeswoman has not said whether agents are questioning anyone in connection with the case.
Authorities have not released a motive for why the letters were mailed this week.
Despite the hazmat suits, officials say apartment residents are not at risk, and people were seen coming in and out of the building.
Ricin is a highly toxic substance. Tiny amounts can be deadly if inhaled or ingested.
There have been no reports of illness connected to the letters.