A bombing near playing children and other insurgent strikes killed 18 people in Iraq on Saturday, challenging government efforts to promote a sense of stability by preventing attacks during a major Muslim holiday.

The bloodshed underscored the difficulties facing Iraq's leadership as it struggles to keep its citizens safe. Authorities had increased security in hopes of preventing attacks during the four-day Eid al-Adha celebrations, when people are off work and families gather in public places.

The deadlier of two blasts in Baghdad struck near playground equipment that had been set up for the holiday in a market in the eastern neighborhood of Bawiya. Police officials said eight people were killed, including four children. Another 24 people, including children, were wounded, they added.

"Nobody expected this explosion because our neighborhood has been living in peace, away from the violence hitting the rest of the capital," said Bassem Mohammed, a 35-year-old father of three in the neighborhood who was startled by the blast.

"We feel sad for the children who thought that they would spend a happy time during Eid, but instead ended up getting killed or hurt."

Elsewhere, a bomb attached to a bus carrying Iranian Shiite pilgrims killed five people and wounded nine, according to police. The bomb, hidden on the underside of the bus, detonated as the pilgrims were heading to a Shiite shrine in Baghdad to mark Eid, a major Muslim holiday.

Authorities have said they planned to increase the number of checkpoints, shut some roads and deploy extra personnel during the holiday period.

They are also relying more on undercover intelligence agents, said Lt. Col. Saad Maan Ibrahim, a spokesman for the interior ministry. He emphasized that both bombings took place on the edge of the capital rather than in densely populated areas.

"The terrorists apparently weren't able to get to the heart of the city. So they chose to attack soft targets on the outskirts," he said.