Iraqi troops opened fire on stone-throwing Sunni demonstrators in the country's volatile west, leaving five dead in the first killings of protesters in more than a month of anti-government rallies.
The violence is likely to exacerbate tensions between the Shiite-led government and minority Sunnis angry over perceived second-class treatment and what they see as unfair policies targeting their sect.
Hours after the shooting, police said gunmen attacked an army checkpoint, killing two soldiers, in apparent payback for the earlier bloodshed. At least one army vehicle was set ablaze, and dozens of civilian gunmen were seen roaming the streets before local authorities imposed a curfew in the city.
The protest was part of a wave of rallies which first erupted in Anbar province last month after the arrest of bodyguards assigned to Sunni Finance Minister Rafia al-Issawi, who comes from the area. Anbar is a former al Qaida stronghold which saw some of the fiercest fighting against US forces during the war.
The protesters are demanding the release of detainees and the cancellation of a tough counter-terrorism law and other policies they believe overwhelmingly target Sunnis. Many link their cause with the broader Arab Spring and are calling for the downfall of the government altogether.
Prime Minister Nouri al-Maliki's government has done little to crack down on the protests and has released hundreds of detainees in a concession to the protesters' demands. But he has also criticised some in their ranks for seeking to undermine the democratic process and exacerbate the country's sectarian divisions.
In a statement issued after the shooting, Mr al-Maliki urged government security forces to show restraint and avoid the use of force. He also called on demonstrators not to provoke the army.
At the same time, he suggested unruly protesters were to blame for the incident.
"Today, in a deliberate act, a group of misguided people attacked one of the army's checkpoints. They started their assault using rocks and then shooting followed, and this has caused causalities and a rise in tension that al Qaida and terrorist groups are trying to take advantage of," he said.