HOUSTON - Two people were taken to the hospital after they were exposed to a "white powdery substance" in a package found at Ted Cruz's campaign office on Tuesday.

Cruz's office said they received a piece of mail addressed to Senator Cruz Tuesday morning. When the mail was opened, it contained the white powdery substance.

Staff members alerted building security and local law enforcement.

The office says the two people hospitalized were not Cruz's staff members. We're told they were taken to the hospital as a precaution.

The 9th floor of the Phoenix Tower was evacuated after the package was found, HFD said in a tweet.

"The building is still secured for entrance and exits by fire and police. We don't yet know what was the substance," Cruz's office said in a statement.

HFD HazMat was on the scene Tuesday morning and working to determine the nature of the substance.

At 12:40 p.m., HFD sent out an update on Twitter saying the evacuation was lifted and all tests for any hazardous material were negative.

The FBI is now investigating the incident.

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There are currently two foreign consulates visiting in the Greenway Plaza at this time.

There have also been reports from the Pentagon about two envelopes suspected of containing ricin found in the Pentagon's mail screening facility on Tuesday.

One envelope was addressed to Defense Secretary Jim Mattis and the other to the Navy's top officer, Adm. John Richardson.

The FBI is now investigating that incident as well.

It's unclear if the two incidents are related.

MORE: Pentagon: Packages that may contain ricin found on grounds