MITCHELL, SD (Mitchell Now) — U.S. Sen. Mike Rounds’ Sioux Falls office was evacuated after receiving a suspicious letter, according to a statement from the South Dakota Republican.

Rounds said staff members followed protocols recommended by U.S. Capitol Police and contacted the Sioux Falls Police Department. Local officers responded to investigate and evacuate the office.

An earlier warning from Capitol Police, which Rounds said had intercepted other letters, helped staff recognize the suspicious mail before opening it.

Rounds said the office would remain closed for the rest of the day while police investigated, with normal hours expected to resume Monday morning.

He thanked responding officers and his staff, saying “I am also grateful for all of my team members, who work tirelessly on behalf of South Dakotans despite the risks involved”

“This has no place in our nation. America is better than this,” Rounds said.