The Jacksonville offices of Florida Sens. Bill Nelson (D) and Marco Rubio (R) received suspicious packages containing a white, powdery substance early this week.

Nelson’s office was evacuated Monday and Rubio’s on Tuesday after staff opened a package containing a white, powdery substance accompanying a threatening letter.

Neither substance was found to be dangerous or toxic, according to Senate Sergeant-at-Arms Terrance Gainer.

The FBI’s Jacksonville office has opened an investigation into the two mailings, according to FBI Special Agent Jeff Wescott.

“We think the two incidents are connected because of similarities in the mailings,” he said. “We’re actively pursuing a number of leads.”

Both offices responded quickly to the mailings.

“They both followed very good procedures, evacuated the office, called the local police and us,” Gainer said.

“It was a scare, but, ultimately, it was determined that the substance was harmless and our Jacksonville team continued with their business the next day,” said Rubio spokesman Alex Burgos. After the incidents, Gainer’s office sent an email warning all D.C. Senate offices and similarly alerted the House of Representatives. Although the Sergeant-at-Arms Office said it is confident that mail sent to Members’ Washington, D.C., offices is clean and not dangerous, mail sent to district offices does not receive the same security procedures.

To protect district staff, the SAA developed a portable “Postal Sentry” device for opening suspicious mail. The device contains any powders or substances that might be harmful. All state offices are encouraged to use such devices, though it isn’t mandated.

One of the two Jacksonville offices had a Postal Sentry system in place early this week, while the other did not. Gainer declined to specify which office used the system, citing security concerns.

The other office is now in the process of obtaining one.

“It takes up a little room, so I understand the frustration in small state offices about having this thing there, but it’s another safety precaution,” Gainer said.