Four Iraqis were killed and 13 were injured, hospital and militia officials said. Witnesses say the fighting was sparked off when Iraqi police attempted to arrest a number of suspected militants, reports CBS News Correspondent Charles D'Agata.
Gunmen loyal to radical cleric Muqtada al-Sadr took control of the Ghari police station, which is 250 yards from the Imam Ali Shrine, witness Mohammed Hussein said. The station was looted and police cars were burned.
"We sent a quick reaction unit to assist the policemen defending the station, but they were overwhelmed by al-Sadr fighters," said Najaf Gov. Adnan al-Zurufi. "We will solve this problem as soon as possible. We will ask for the help of the Americans, if necessary."
Meanwhile, fighting ebbed Thursday around the main police station, which came under fire Wednesday night when the attacks began.
In other developments:
U.S. forces were not involved in the clashes, and it was unclear whether the violence marked the end of the cease-fire in Najaf, mediated by Shiite leaders and al-Sadr's militia, or resulted from police attempts to crack down on petty crime in the city.
Police and witnesses said trouble started when authorities tried to arrest some suspected thieves at the bus station near the main police headquarters. Masked attackers, possibly including some of al-Sadr's militia, responded with machine gun fire and rocket-propelled grenades near the headquarters building.
One gunman was killed when police returned fire, al-Sadr's spokesman Qais al-Khazali said. The slain man's armed relatives attacked the headquarters again Thursday in revenge. Fighting later moved to the second station.
"We are trying to convince them to stop shooting," al-Khazali said. "We are still committed to the truce."
Two of the four dead were al-Mahdi fighters, and several others were injured, al-Khazali said.
Last week, al-Sadr agreed to send his fighters home and pull back from the Islamic shrines in Najaf and its twin city of Kufa, handing over security to Iraqi police. The U.S. Army also agreed to stay away from the holy sites to give Iraqi security forces a chance to end the standoff.
The clashes illustrate the chaotic situation in Iraq as the U.S. military begins phasing down its operations ahead of the transfer of sovereignty in June.
One senior U.S. military official, speaking on condition of anonymity, said coalition forces would not leave the streets immediately after June 30 but would phase down their presence as Iraqi security troops gradually take control.
"There is a difference between the abrupt handover of sovereignty that will be done on the political side, to the gradual handover of the Iraqi security," the senior official said. "We have taken a bottoms up approach since day one in training up the Iraqi security forces … We are concentrating now on the higher level staffs."
The Kurds expressed fears they will be sidelined politically by the Shiite Arab majority, despite assurances from Prime Minister Iyad Allawi and others that the new government would stick by its commitments for communal rights.
U.N. diplomats said the decision was made to keep a reference to the interim constitution — the Transitional Administrative Law — out of the resolution to appease Iraq's most influential Shiite cleric, Grand Ayatollah Ali al-Husseini al-Sistani, who grudgingly accepted the charter when it was approved in March.
Barham Salih, 44, of the Patriotic Union of Kurdistan and an American favorite, announced Wednesday he would not accept the post of deputy prime minister for national security unless the powers were spelled out "appropriate to the position, sacrifice and important role of the Kurdish people," the PUK's KurdSat television reported.