Suspicious, white powdery substance found in two letters sent to Rep. Norma Torres’s Ontario district office on Wednesday turned out to be “nonthreatening.”

Interns and staffers discovered the letters, prompting hazmat teams to descend on the site, Torres said in a statement.

Hazmat officials and local law enforcement investigators determined the powdery substance was “non-threatening,” Torres said on the social media site X late Wednesday. “Members of my team are safe and have returned to their homes” after initially sheltering in place.

Marysol Ibarra, a spokesperson for Torres’s office, said via email that the investigation is ongoing.

“Local law enforcement and the United States Capitol Police continue collaborating on further investigation about the suspects as well as the exact composition of the substance,” Ibarra said on Thursday. Testing of the substance could take days or weeks but “it was confirmed on-site upon initial review to be non-threatening.”

Torres initially described the incident as an “attack.”

In a statement, Torres said no one experienced any symptoms, potentially from the powder, and that U.S. Capitol Police and local law enforcement were notified.

Torres’s district office is in Ontario, but the district spans from Fontana to Chino to Pomona.