A bomb blast near Shi'ite pilgrims traveling to Iraq's holy city of Karbala killed at least two people on Saturday, while two others were killed in a Baghdad bombing.

Iraqi officials say at least 15 people were wounded in the blast near Karbala, where thousands of Shi'ite pilgrims are gathering for a religious festival. Two other people died in bombing near the city on Friday.

Meanwhile, officials say a bomb placed near a vehicle in Baghdad exploded on Saturday, killing at least two people.

The incidents took place as the U.S. moves ahead with plans to remove its forces from Iraq by the end of the year. Both U.S. and Iraqi officials have expressed concern about Baghdad's ability to cope with security after the pull-out.