Thousands of pilgrims arrive in Karbala to mark the birth anniversary of Shi'ite Imam Al-Mehdi

Hundreds of thousands of Shi'ite pilgrims gathered in Iraq's holy city of Karbala for a religious festival.

Iraqi authorities expect the number of pilgrims to top one million. Heavy security is in place across the city during the festival commemorating the birth of ninth-century Imam al-Mahdi al-Muntadar.

In other developments Saturday, bomb attacks in Baghdad killed at least two people. And, a gunman killed an employee of Iraq's government-run newspaper in the capital.

Iraqi officials also announced Prime Minister Nouri al-Maliki is heading to Iran Monday. Officials say his two-day visit will focus on security and bilateral issues.

On Friday, insurgents firing mortar rounds killed at least three Shi'ite pilgrims in a procession near Karbala. Officials say at least six more pilgrims were wounded.

In other violence, a roadside bomb in Baghdad killed at least two people.