Another bomb attack targeting the Shi'ite pilgrims, who are coming to Baghdad to attend the ceremony of Arbaeen, led to the death of three on Monday, just a day after a similar attack caused the death of at least 40 Muslims south of Iraq’s capital.

Local authorities said the roadside bomb also wounded more than 15 pilgrims as they were on their way to the central city of Karbala for one of Shi'ite Islam's holiest congregations.

Earlier Sunday, before the carnage in which 40 people died and another 60 were wounded, another attack took place in Baghdad in which at least three Shi'ite pilgrims died and 36 others were wounded.

The al-Qaeda terrorists are suspected for the ferocious attacks, the U.S. Embassy in Baghdad and the U.S. military in Iraq said.

Another suicide bomb attack took place in Baghdad as a man in a wheelchair blew himself up inside a police building, killing a senior police officer. The man in the wheelchair entered the building and asked for deputy police chief Major-General Abdul-Jabbar Rabee Muttar. When Muttar approached the apparently disabled man, he blew himself up, the VOA wrote on its Website. Two police officers were wounded in the blast.

The tens of thousands of Muslim pilgrims heading to the central shrine city of Karbala from across the country to attend the Arbaeen ceremony are very vulnerable to terrorist attacks.

Authorities expect millions of pilgrims to attend the commemoration, but despite deploying about 40,000 police officers in the area, it seems that the local authorities can not cope with the problem.

The ceremony of Arbaeen commemorates the 40 days following the anniversary of the martyrdom of Immam Hussein, the grandson of the Prophet Mohammed, by armies of the Sunni caliph Yazid in a battle in 680.

The Sunni militants are also suspected for carrying out the suicide attacks. The militant often attacked Shi'ite religious observances.