BAGHDAD, Sept. 20 (Xinhua) -- Hundreds of thousands of Shiite Muslims rallied at holy sites of Iraq's Karbala and Kadhmiyah for the annual religious ritual of Ashura on Thursday amid tight security measures.

Shiite pilgrims from Iraq and other countries, including Iran, flocked into Karbala, some 110 km south of the capital Baghdad, and into Kadhmiyah district in northern Baghdad.

They commemorated Ashura, which marks the death of Imam Hussein, grandson of Prophet Mohammed, who was killed and buried in 680 A.D. in Karbala.

Dozens of tents were set up on the streets leading to the shrine to serve water, food and medication to the pilgrims.

In Kadhmiyah, people clad in black and accompanied by drummers were marching in lines in honor of Imam Hussein.

In Karbala, where the tomb of Imam Hussein locates, hundreds of thousands of Shiite pilgrims converged to commemorate the climax of the Shiite religious rite of Ashura.

Processions of elderly, young men and children marched through thousands of other pilgrims, waving green, black and red flags at the wide avenue in front of Imam Hussein shrine in Karbala.

The Shiite ritual was held under tightened security measures as hundreds of Iraqi security troops manned dozens of checkpoints and patrol across Baghdad.

More than 30,000 security members with hundreds of civilian guards were deployed in and around the city of Karbala and Baghdad's Kadhmiyah district to protect the worshippers, according to security officials.

Ashura, meaning "ten" in Arabic, takes place on the 10th day of Muharam, the first month in the Islamic lunar calendar.