BEIJING (Reuters) - Chinese police on Monday evacuated Beijing's Tiananmen Square, the site of 1989 pro-democracy protests bloodily suppressed by the government, following a fire after a car ran into a crowd, a Reuters witness and state media said.

The Communist Party's official People's Daily said on its website that a car had caught fire. Xinhua news agency, in a brief dispatch in English said that "a motor vehicle went into the crowd".

Neither gave details.

Beijing police, reached by telephone, said they had no information. The Beijing government, also reached by telephone, said it did not know what had happened.

The Reuters witness said he saw fire engines, an ambulance and numerous police cars heading in the direction of the fire, which sent a plume of black smoke into the sky. The main road through the square was closed.

The fire was on the north side of the square close to the main entrance of the Forbidden City, upon which hangs a portrait of the founder of Communist China, Mao Zedong. It was not clear if the fire was on the road or the pavement or the square.

A foreign tourist who was on the square and asked not to be identified said she heard an explosion followed by a fire.

Tiananmen Square is always under heavy security due to its proximity to the Zhongnanhai compound of the central leadership and the Great Hall of the People, where the country's largely rubber stamp parliament meets.

(Reporting by Maxim Duncan; Writing by Ben Blanchard; Editing by Nick Macfie)