Three car bombs exploded almost simultaneously in a Shiite Muslim neighborhood of Baghdad after dusk Wednesday, killing at least 19 people. The attacks appeared to be a new attempt to inflame Iraq's sectarian divisions.

The bombs detonated about 9:45 p.m. in the Shuala district, a working-class neighborhood on the city's northern outskirts, witnesses said. News organizations reported that 48 people were wounded.

Residents of the neighborhood said that, unlike recent bombings that have struck Iraqi security forces, the attack took place in an area that had no police stations or other obvious security targets. The Associated Press reported that two of the bombs exploded at restaurants, while the third was directed against a bus station.

With a Shiite-led government in power for the first time in the country's modern history and an insurgency driven by the rival Sunni Muslim minority, Iraq faces sectarian tensions that some say could lead to civil war. Attacks on Shiite civilians that serve to heighten those tensions are widely assumed to be the work of Sunnis.

The insurgents also target Sunnis who cooperate with the government and U.S. and allied military forces.

Hours before the bombings, gunmen opened fire on a car carrying a Sunni politician and legal scholar, Jasim Isawi, and his 18-year-old son, killing them both. Isawi, a former judge and lecturer at Baghdad's College of Islamic Sciences, had earlier been one of several Sunnis nominated to join a committee that is working to write a new constitution for Iraq, according to Salih Mutlak of the National Dialogue Council, a Sunni group. He was not among those currently being considered for inclusion.

Meanwhile, the Iraqi Islamic Party, a leading Sunni organization, announced that one of its members, Abdul Sattar Khazraji, a college professor, died Wednesday after he was shot four times the previous day while on his way to work.

Mutlak said Wednesday that he believed there was "a campaign against Sunni politicians, who have become soft targets. We don't want to have an immediate reaction concerning these assassinations, but if these operations continue, I think many Sunni politicians will stop their participation" in the political process.

Leaders from almost all of Iraq's religious, ethnic and political factions have agreed to try to draw more Sunnis into the political process and away from the nearly two-year-old insurgency. But the process has moved haltingly. During a time of continuing uncertainty, insurgents have carried out frequent attacks on targets that appear calculated to turn Sunnis and Shiites against one another.

The violence in Baghdad continued shortly after dawn Thursday when five explosions shook the Karrada neighborhood, across the Tigris River from the Green Zone, which houses foreign embassies and government offices.

Four car bombs exploded in rapid succession -- one of them outside a Shiite mosque -- about 7:10 a.m., a Defense Ministry spokesman said. In addition, a mortar shell struck near Karrada Hospital, a private clinic.

The ministry did not have immediate casualty reports, but the Reuters news agency reported that at least three people were killed.

Elsewhere, insurgent attacks on U.S. and Iraqi security forces continued. A suicide bombing Wednesday night apparently targeting an Iraqi army patrol in the Ameriyah district of central Baghdad killed at least four bystanders, the Associated Press reported.

In the northern city of Mosul, a car bomb that detonated near a U.S. military patrol killed three Iraqi civilians and wounded seven, the Reuters news agency reported. And U.S. Marines reported that small-arms fire killed two U.S. Army soldiers on Tuesday near the western city of Ramadi.

On Wednesday, a roadside bombing apparently targeting a U.S. military convoy west of Ramadi killed an Iraqi civilian and injured three.

A group of children on bicycles ran over a concealed bomb in Baqubah, northeast of the capital, the Associated Press reported. A 9-year-old boy was killed and two others, ages 6 and 7, were wounded.

In the town of Madain, southeast of Baghdad, a roadside bomb struck an Iraqi police patrol, killing two policeman and wounding two others, the Associated Press reported.

In a separate development, a Filipino held hostage in Iraq since November was released unharmed Wednesday after months of negotiations, according to Philippine government officials quoted by the Reuters news agency.

Robert Tarongoy, an accountant working for a Saudi contractor, was taken hostage on Nov. 1 along with five co-workers when gunmen stormed their villa in Baghdad. Four of the workers were quickly released, but officials believe the hostage-takers are still holding an American, Roy Hallums.

Special correspondents Naseer Nouri and contributed to this report.