WASHINGTON: Two police officers were shot early Thursday amid protests in the flashpoint American town of Ferguson over the treatment of blacks by the mainly white police force, a newspaper said.

The St. Louis Post dispatch said the two officers were shot near the police station in the small Missouri town. The extent of their injuries was not immediately known.

Witnesses reported two to four shots, the paper said.

It quoted a police source as saying one police officer was a St. Louis County officer and the other from a town near Ferguson.

Police were confronting protesters outside the police station when the shots were fired, the paper said.

Earlier in the day, the Ferguson police chief resigned over a scathing US Justice Department report into the fatal shooting of unarmed black teenager Michael Brown by one of his officers.

Last summer Brown was shot and killed by white police officer Darren Wilson, igniting angry protests and a national debate about race and law enforcement in America.

Wilson was not charged in that death.