A series of explosions struck the northern city of Kirkuk on Tuesday, killing at least 15 people. Iraq's prime minister promised to show "no mercy" to terrorists and said his long-awaited security plan for Baghdad will include a curfew and banning weapons.

The attacks in Kirkuk began at 7:45 a.m. local time when a parked car containing a bomb exploded near a police patrol in the city center, killing 10 people, including two policemen, Brig. Gen. Sarhat Qadir said. Nine people were wounded.

Some 30 minutes later, guards opened fire on a suspected suicide car bomber trying to pass through a checkpoint at the Kirkuk police directorate. The car exploded, killing five people, including two policemen, and wounding six, Qadir said.

Another suspected suicide car bomber tried to hit a Kurdish political office in the oil-rich city about 180 miles north of Baghdad at 8:30 a.m., but guards opened fire on that car, and it exploded, police Col. Taieb Taha said. Three civilians were wounded.

A suicide car bomber targeted a police patrol south of Kirkuk more than an hour later near an institute for the disabled. The explosion killed the driver of a car and wounded six, Qadir said.

Countrywatch: Iraq

Facing unrelenting violence following the death of terror leader Abu Musab al-Zarqawi last week, Prime Minister Nouri al-Maliki promised a security crackdown in the capital of Baghdad, which has been hardest hit by the insurgency. He said the plan "will provide security and confront the terrorism and ... enable Iraqis to live in peace in Baghdad."

"The raids during this plan will be very tough ... because there will be no mercy toward those who show no mercy to our people," he said in a news release distributed Tuesday.

The Shiite prime minister said the plan will include securing roads in and out of Baghdad, banning people from carrying weapons and implementing a 9 p.m.-6 a.m. curfew. He did not provide more details, saying the plan would be formally announced within the next two days.

But an Interior Ministry official, who spoke on condition of anonymity because he is not authorized to talk to the media, said the plan also would include putting more police on the streets, increasing checkpoints and carrying out raids against suspected insurgent hideouts.

Al-Maliki is seeking to build on momentum after scoring major victories last week with the killing of Zarqawi and the appointment of new security ministers. He also planned to talk to President Bush later Tuesday via a secured video teleconference.

Bush sought to reassure Iraqis on Monday that the United States stands ready to help their new government, but he cautioned that success largely depends on Baghdad's ability to secure the nation and care for its citizens.

"The best way to win this war against an insurgency is to stand up a unity government which is capable of defending itself, but also providing tangible benefits to the people," Bush said at the start of a two-day strategy session on Iraq at Camp David.

More than 200 raids have been carried out since Zarqawi's death last Wednesday, some directly connected to what the U.S. military has described as a "treasure trove" of intelligence gleaned from his safehouse. U.S. troops killed seven insurgents in a raid Monday that also left two children dead not far from the U.S. bombing raid that killed al-Zarqawi.

"As far as the Al Qaeda network, we're ... cautiously optimistic that we have been very successful thus far in the ongoing operations over the last five days," Maj. Gen. William Caldwell, a U.S. military spokesman in Baghdad, said Monday. "We realize this is not going to end the insurgency and that it's really going to take the people of Iraq making that decision."

Caldwell also said a "high-value individual" with a $50,000 price on his head was detained. He did not name the suspect, but said he was picked up based on a tip.

He said the killing of the two children in Monday's raid was "extremely unfortunate."

"Any time we're out conducting operations against terrorist elements and they mix themselves in with innocent young women and children and civilians, they in fact are asking for that possibility to occur," he said.

The raid came as insurgents escalated their attacks, killing more than 50 people across the country Monday in a bid to show they were not defeated after Zarqawi's death. The top health official in the volatile Diyala province northeast of Baghdad, the area where Zarqawi was killed, also went missing Monday after a meeting with Iraq's health minister in the capital.

In other violence Tuesday, according to police:

• Iraqi police found eight bodies, including one policeman, in western Baghdad.

• A professor at the Engineering College of Baghdad University was gunned down in a drive-by shooting as he was leaving his house in the upscale Mansour neighborhood.