HOUSTON (AP) — A spokeswoman for Republican Sen. Ted Cruz says a package addressed to Cruz's Houston campaign headquarters caused a lockdown, which was later lifted. 
 
 The Houston Fire Department says two people were taken to a hospital Tuesday after apparently being exposed to a "white powdery substance," though it didn't provide details about the two people or say whether they are fine. 
 
 Cruz's spokeswoman, Catherine Frazier, says no one from Cruz's staff was taken to the hospital. 
 
 The fire department tweeted that tests for hazardous substances were negative after the building floor where Cruz's office is located was evacuated. 
 
 Frazier says the package was opened in the lobby, and that the authorities locked down the lobby and elevator for a couple of hours. 
 
 It comes on the same day that authorities at the Pentagon say they found at least two packages believed to contain ricin, a deadly white powdery poison made from castor beans. ||||| WASHINGTON—Two letters that arrived at a Pentagon distribution center have tested positive for the poison ricin and a “suspicious envelope” had been sent to the White House, defense officials and the Secret Service said Tuesday. 
 
 The letters sent to the Pentagon were addressed to Defense Secretary Jim Mattis and Adm. John Richardson, the chief of naval operations, an official said. 
 
 It...
– Ricin has been detected in two pieces of mail that arrived at a Pentagon mail distribution center, defense officials announced Tuesday. The building is near, but not in, the Pentagon; the mail was addressed to Defense Secretary Jim Mattis and Adm. John Richardson, the Chief of Naval Operations. After the poison was detected, all mail received at the mail-screening facility Monday was put under quarantine, a Pentagon spokesperson says. The FBI took possession of the envelopes in question and is leading the investigation, including conducting further tests, the Wall Street Journal reports. The mail initially caused suspicions because it contained a sticky substance, per a defense official. Also Tuesday, a package addressed to Ted Cruz's Houston campaign headquarters caused a lockdown, the AP reports. A spokesperson for the Republican senator says the package was opened in the lobby and two people—not members of Cruz's staff—were exposed to a "white powdery substance" and taken to a hospital. Their conditions were unknown. The fire department tweeted that all tests for hazardous substances came back negative. The lockdown has since been lifted.