The Kansas City branch for the Federal Bureau of Investigation released a statement on Tuesday addressing testing done on a series of letters containing suspicious white powder that were sent to public officials in the state last week.

FBI said that testing of the substance so far has shown no indication of a risk to public safety.

More than 30 letters containing the white powder were sent to the Kansas Attorney General’s office as well as state legislators. The Kansas Bureau of Investigation said the letters were sent across the state.

Over the weekend, the KBI issued a press release saying that lab testing of the powder came back “presumptively negative for common biological agents of concern.”

Both the KBI and FBI have said that additional testing will be conducted in order to fully characterize the material in the letters. The Kansas Dept. of Health and Environment and other agencies are assisting.

The KBI also said in a statement that the investigation has expanded beyond Kansas, so the FBI will now lead the investigation after reports of similar letters being sent to former President Trump and Supreme Court Justice Clarence Thomas. 

The KBI said it will continue to work with all law enforcement partners to bring these incidents to appropriate resolution.

Since the first letters were handled and reported by officials, the KBI had over 60 special agents, forensic scientists and employees devoted to safely collecting or screening evidence, or managing and tracking response to the incidents. Additionally, 17 hazmat teams and 12 bomb squads responded across the state.

Officials said to report any letters containing an unknown white powder to the KBI at 1-800-KSCRIME or the FBI at 1-800-CALL-FBI or tips.fbi.gov.

Authorities said they are working to determine who sent the letters and why, and just how many letters were sent.