Washington, Oct 17 (IANS): A Republican Party office in North Carolina was firebombed in an attack that presidential candidate Donald Trump blamed on "animals representing Hillary Clinton", despite the Democratic candidate also condemning the incident.

The firebomb was thrown on Saturday night through a window of the office in the predominantly Democratic Orange county, charring furniture and campaign posters, but caused no injuries, the police said.

A swastika and the phrase "Nazi Republicans get out of town or else" were also spray painted on the facade of a nearby building, EFE news reported.

Trump blamed the incident on "animals representing Hillary Clinton and Democrats in North Carolina" in a message on Sunday on his official Twitter account, and said he would never forget the attack.

The Republican candidate added that the attack was launched "because we are winning" given the tight contest in North Carolina, key swing state in the November 8 presidential elections and where Clinton was leading the polls by a narrow margin.

The Democratic candidate also condemned the incident in a tweet, calling it "horrific and unacceptable" and added she was "very grateful that everyone is safe".

North Carolina Governor Pat McCrory, a Republican, called the firebombing "an attack on our democracy".

"Violence has no place in our society - but especially in our elections. Fortunately no one was injured; however, I will use every resource as governor to assist local authorities in this investigation," he said in a statement.

Dallas Woodhouse, executive director of the Republican Party in North Carolina, called the attack an "act of political terrorism".

"This is a horrific, horrific act of political terrorism, one that we will not succumb to and one that we will answer. When people try to stifle freedom of speech and freedom of assembly, you must come back with more speech and aggressively defend your rights," Woodhouse said.