TAMPA, Fla. -- A report of a suspicious powder shut down the Hillsborough County Courthouse Annex and nearby streets Wednesday afternoon in downtown Tampa, officials say. The all clear was sounded about 6 p.m.

Officials say the sample found at 401 N. Jefferson St. was negative, but they will send it to the lab just in case.

About 3:40 p.m., the call was received and several agencies responded: Tampa Fire Rescue, Tampa Police Department and Hillsborough County Sheriff's Office.

A court worker had opened a letter that contained a powdery substance, according to the sheriff's office. Other people in the room quarantined themselves and alerted 911.

A Fire Rescue hazmat team dressed in protective gear performed a medical assessment of the affected people. The team determined that the powder was nontoxic.

Other people in the room were able to safely evacuate by 5:45 p.m.

A sample of the powder will undergo further testing. No injuries were reported.

The sheriff's office has started a criminal investigation to identify who sent the substance, who was the intended targeted and what was the motive.