Baghdad, Iraq ? Eight suicide bombers struck in quick succession Saturday in a wave of attacks that killed 55 people as Iraqi Shiites marched and lashed themselves with chains in ritual mourning of the 7th century death of a leader of their Muslim sect. Ninety-one people have been killed in violence in the past two days.

For the second year running, insurgent attacks shattered the commemoration of Ashoura, the holiest day of the Shiite religious calendar, but the violence produced a significantly smaller death toll than the 181 killed in twin bombings in Baghdad and the holy city of Karbala a year ago.

The dead this year included a U.S. soldier who was killed in Baghdad when American troops responded to calls for assistance from Iraqi forces unable to cope with a slew of attacks.

With majority Shiites poised to take control of the country for the first time in modern Iraqi history, the interim government and Shiite politicians vowed the bloodshed would not cause the nation to spiral into civil war.

The suicide bombings were attempts “to create a religious war within Iraq. Iraqis will not allow this to happen, Iraqis will stand united as Iraqis foremost, and Iraq will not fall into sectarian war,” Mouwaffaq al-Rubaie, the national security adviser for the interim government, told The Associated Press.

“The bombings on Shiite mosques and shrines on Ashoura by terrorists that call themselves Muslims are in fact actions by terrorists only attempting to spill even more Muslim blood by encouraging sectarian violence,” he said.

The Saturday carnage was the deadliest of any day since last month’s elections for a new national assembly in which the Shiite ticket, the United Iraqi Alliance, won 48 percent of the vote in Iraq’s first democratic balloting. The alliance was expected to name its candidate for prime minister in the coming days. Forty-four people died in election-day violence.

As the violence ravaged the country, a five-member U.S. Congressional delegation including Sen. Hillary Clinton, the New York Democrat, met with Iraqi government officials in Baghdad’s heavily fortified Green Zone.

“The fact that you have these suicide bombers now, wreaking such hatred and violence while people pray, is to me, an indication of their failure,” Clinton told reporters.

Bayan Jaber, a leading member of the Shiite Supreme Council for the Islamic Revolution in Iraq, or SCIRI, said the attacks had failed to create a divide between Shiites and the Sunni Arab minority. Shiites account for about 60 percent of Iraq’s 26 million people. The Sunnis make up 20 percent of the population, but dominated politics under Saddam Hussein and previous governments after Iraq gained independence from Britain.

Jaber called the attackers a small faction of Sunnis “who are extremist Wahhabis who want to spark a civil war in Iraq.” But, he added, “a sectarian war will never occur in Iraq because Iraq is not like Afghanistan or Pakistan. We have tribal, marital, and historical relations with Sunnis and nothing will affect it.”

The death toll built rapidly Saturday as the insurgents mounted attacks throughout the country employing suicide bombers — responsible for most deaths — mortar fire and gunmen, said Capt. Sabah Yassin, a defense ministry official.

One of the deadliest attacks was the work of a suicide car bomber at an Iraqi army checkpoint in Latifiya, 20 miles south of the capital, killing nine Iraqi soldiers.

At least seven other bombers staged attacks in Baghdad and the region. Explosions reverberated in the capital throughout the day and into the night.

It was unclear which of the attacks in Baghdad claimed the life of the American soldier. A second soldier was wounded in the assault, which also killed an Iraqi, the military said.