Maj. Gen. Tariq Yousif, the police chief of Anbar province, of which Ramadi is the capital, said four prisoners escaped from the city's al-Forsan police station. The U.S. military said it had the same numbers for killed and wounded but said only three escaped.
According to Yousif, the incident started when a prisoner held in a cell with 11 others asked a guard to allow him to go to the bathroom. When the guard opened the cell door, the prisoners pulled him in, grabbed his assault rifle and killed him, then attacked other police.
Some of the detainees managed to escape in the ensuing riot.
The police chief said the prisoners were all suspected insurgents of the group al-Qaida in Iraq. A curfew was imposed in the city, 115 kilometers (70 miles) west of Baghdad as police searched for the escapees. No other details were immediately available.
Iraq's government took over security for Anbar province from the U.S. military in September. Iraq now controls security in 13 of Iraq's 18 provinces.
Anbar is the largest Iraqi province, stretching from the western gates of Baghdad to the borders of Syria, Jordan and Saudi Arabia. It was once the center stage in the Sunni insurgency, which broke out soon after the U.S.-led invasion of 2003 toppled Saddam Hussein's Sunni-dominated regime.
In late 2006, however, Sunni tribes turned against al-Qaida in Iraq because of its brutal tactics, including mass killings of Shiite civilians and its attempt to impose strict Islamic rule. The tribes joined with U.S. forces to push al-Qaida out of the province, and now Anbar is considered one of the quieter parts of the country.
The majority of the U.S. Marine Corps's 22,000 troops in Iraq are based in Anbar.