BAGHDAD, Iraq - A car bomb exploded near a police station in the western Iraqi city of Haditha today, killing 10 people in a second day of violence that highlighted insurgents' disregard for the country's interim government.

Police apparently thwarted a second attack in Karbala, where police chased a car after receiving a tip it was filled with explosives. The two people inside detonated their bomb, killing only themselves and causing no other casualties.

It was the second bloody day in a row in Iraq. On Wednesday, gunmen in northern Iraq assassinated a provincial governor and a suicide attacker detonated a car bomb outside the fortified enclave housing the headquarters of Iraq's interim government, killing at least 10 people.

The bombing - which also wounded 40 people - was the worst attack in the capital since the United States transferred power to the Iraqis on June 28.

Interim Prime Minister Iyad Allawi said Wednesday's bombing was retaliation for the government's arrests of terror suspects. Police said they rounded up over 500 suspected criminals in one sweep this week.

Hours later, insurgents tossed hand grenades and fired machine guns at a convoy transporting Nineveh Gov. Osama Youssef Kashmoula, killing him and two of his guards, Iraqi and U.S. military officials said. Mosul is the largest city in Nineveh province.

Kashmoula was attacked between the cities of Beiji and Tikrit north of Baghdad as he headed to the capital, the U.S. military said.

Insurgents have repeatedly attacked local officials who are seen as being collaborators with American forces, but had not killed an official as senior as Kashmoula since the assassinations last month of Iraq's most senior career diplomat and a top Education Ministry official.

Few details were available about today's car bombing, which appeared to target the main police station, said Col. Adnan Abdel-Rahman, the spokesman for the Iraqi Interior Ministry. Three officers were among the dead, he said.

Haditha is a rural area known as a stronghold of Saddam Hussein's ousted regime, located 120 miles west of the capital.

Around the same time today, saboteurs damaged oil pipelines at separate sites in Iraq's north and south, while insurgents gunned down an officer with the state-run oil company.

The trouble on the southern line occurred in the al-Askari district, 12 miles southwest of Basra. Saboteurs drilled holes into the pipeline; authorities suspect the damage was caused by smugglers.