BAGHDAD - Three large car bombs rocked well-known Baghdad hotels on Monday, killing at least 36 people and ending a 1-1/2-month lull in coordinated assaults on the Iraqi capital as the country heads into a March election.

Police said at least 71 people were wounded in the separate suicide car bombings, which went off within minutes of one another. Some of the casualties were police. Health Ministry data showed a lower figure for the death toll.

The first blast occurred near an entrance of the Ishtar Sheraton hotel, a Baghdad landmark on the eastern side of the Tigris River. The shock wave blew open doors, shattered windows and sent thick dust swirling into the Reuters offices nearby.

A giant mushroom cloud of debris rose from the blast site as ambulances and fire trucks rushed to the scene. Helicopters buzzed overhead and soldiers blocked off entry.

Towering concrete blastwalls protecting the hotel along the Abu Nawas riverside boulevard fell like dominoes. The blast took place across from a park frequented by families and picnickers.

The building has not been a regular hotel for years and largely houses company offices and some media organizations, but some adventurous international tour groups began using it last year.

Zina Tareq, an Iraqi journalist who was in her office at the time of the blast, said she dived under a desk with the five-year-old daughter of a colleague.

We heard a deafening sound. The ceiling collapsed on us and the windows shattered, she said. Another colleague was wounded by broken glass.

Police said another blast went off just outside the al-Hamra hotel, which has been a hub for many Western journalists since the 2003 U.S. invasion. One Western reporter said the hotel had sustained heavy damage. The Washington Post said three of its Iraqi employees were wounded.

Houses collapsed near the Hamra, and civil defense officials searched for survivors. The blast at the Hamra, like that at the Sheraton, ripped a giant crater in the pavement.

A final bomb appeared to have blown up near the Babylon hotel, which is used by Iraqi travelers and sometimes for government meetings.

The area around the hotel has been hit several times in the past year by mortar or rocket fire aimed at the U.S. embassy, located across the river in the heavily guarded Green Zone.

Baghdad security spokesman Major General Qassim al-Moussawi put the death toll at seven killed with 51 wounded, citing Health Ministry data. Death tolls from major attacks have become a political football in the run-up to the March 7 vote.

The last major attack on Baghdad occurred on December 8 when a series of car bombs killed more than 100 people. On October 25 and August 19, a total of around 250 people were killed in suicide assaults on government buildings.

The March ballot is a critical moment for the country as it emerges from the sectarian slaughter unleashed by the 2003 invasion and begins to sign multibillion-deals with global oil firms that could set the stage for future prosperity.

(Additional reporting by Aseel Kami and Ahmed Rasheed; Writing by Michael Christie; Editing by Missy Ryan and Charles Dick)