PORT-AU-PRINCE (Reuters) -Protesting Haitian police officers shot up the army headquarters killing two servicemen and wounding a dozen more during a protest over pay.

The off-duty cops opened fire during a nearly two-hour running gun battle in clashes near the Presidential Palace in Port-au-Prince yesterday.

Media reports said six people were wounded in the attack in the capital by who the Defense Ministry said were gunmen wearing masks.

The clashes were the most violent since police, this time heavily armed, started protesting at the end of last year as the impoverished Caribbean island nation struggles with a prolonged economic and political crisis.

The Haitian government issued a statement late Sunday strongly condemning the violence, calling it an attack against freedom and democracy, noting that it was difficult to assess the scope of the violence.

“Terror reigned in certain areas,” the statement said. “Streets were obstructed and there was a war-like situation at the Champ de Mars (square), where heavy weapons fire was heard almost all day.”

It was not immediately clear who fired the shots or the tear gas during the protest, which led to the suspension of Carnival, a multiday music and dance festival that culminates in a colorful procession.