WASHINGTON, United States (AFP)- Police in the southern US state of North Carolina on Sunday were investigating a firebomb attack on a Republican Party office, with the message “Nazi Republicans leave town or else” sprayed on an adjacent building.

No one was hurt in the arson attack overnight on the Orange County Republican Party headquarters in Hillsborough, the town said in a statement.

The executive director of the state’s Republican Party called the attack “political terrorism.”

“The office itself is a total loss,” Dallas Woodhouse told The Charlotte Observer. “The only thing important to us is that nobody was killed, and they very well could have been.”

Photographs posted by the state party showed the office’s charred walls and furniture, with colourful lawn signs for candidates, including Republican presidential hopeful Donald Trump, appearing melted and warped.

The perpetrators threw flammable material in a bottle through the office’s front window, and spray-painted the words “Nazi Republicans leave town or else” on a business next door, the town said.

The damage was reported by another business owner Sunday morning.

Police were investigating the attack, which Trump blamed on “animals representing Hillary Clinton and Dems in North Carolina… because we are winning.”

“With you all the way, will never forget. Now we have to win. Proud of you all!” the bombastic billionaire said on Twitter.

Clinton, the Democratic nominee, took to Twitter to denounce the incident as “horrific and unacceptable,” adding she was “very grateful that everyone is safe.”