AMMAN, Jordan -- Scores of people were injured Friday as Jordanian protesters demanding reforms clashed with government supporters, pelting each other with stones, as unrest intensified in this key U.S. ally.

Police fired water cannons to disperse the crowd, then hundreds of riot police, some wearing masks, stormed the area, hitting anti-government demonstrators with batons and dragging at least a dozen into a nearby government building.

The clashes were the most violent in more than two months of protests inspired by the popular uprisings in Tunisia and Egypt. Unlike protests in those countries, which toppled longtime rulers, Jordan's protests have not targeted King Abdullah II, instead calling for greater political participation in the kingdom's affairs.

Friday's violence started when about 400 government supporters attacked some 1,500 demonstrators calling for the dissolution of parliament and the firing of the country's prime minister.

Hundreds of anti-government activists -- many of whom met through Facebook -- vowed to camp out in the central square in front of the Interior Ministry in Amman until their demands are met. Their numbers swelled to about 1,000 before Friday's clashes.

The pro-government crowd appeared to disperse as about 400 riot police stormed the square, hitting anti-government demonstrators with batons. An Associated Press reporter saw three police officers, their faces covered with blood, being taken away in ambulances.

The anti-government protesters soon dispersed as well.

Police officials on the scene said they had arrested protesters from both groups, though they gave no numbers. They spoke on condition of anonymity according to police protocol.

A similar clash broke out in the same square late Thursday, injuring 35 people.