An envelope containing some sort of “white powdery substance” was delivered Tuesday to U.S. Sen. Ted Cruz’s campaign office in Houston.
Law enforcers and building security were called as soon as the substance was discovered.
Fire trucks and a hazardous response team were quickly on the scene, news reports show.
Part of the building was locked down for an investigation.
Houston firefighters, who reported that two went to the hospital after being exposed to the powder, eventually tweeted that the evacuation order for the office building had been lifted and “all tests were negative for any hazardous substance.”
The conditions of the two who went to the hospital were unavailable. Cruz staffers said they were not campaign workers.
“Our campaign staff are OK and the building has been given the all clear,” said Catherine Frazier, a campaign spokeswoman.
Also this week, ricin — a toxic compound that can cause death if ingested — was detected in at least two envelopes delivered to the Pentagon’s mail facility.
Cruz, a Republican, faces Democratic U.S. Rep. Beto O’Rourke of El Paso in a fierce Texas-size election battle.
This fight for the U.S. Senate seat has become one of the costliest and most watched races across the country, as many wonder if O’Rourke can do what no other Democrat has done for more than two decades in Texas: win a statewide office.