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Hani Mohammed, Associated Press
Men look at a car destroyed by a recent Saudi-led airstrike in Yemen's capital, Sanaa, Saturday, April 25, 2015. With combatants fighting in neighborhoods and Saudi-led coalition warplanes pounding Iran-backed rebels from the sky, Yemen's war is wreaking a particularly bloody toll among civilians: more than 550 have been killed in the past month, including 115 children, the U.N. said Friday.

SANAA, Yemen — Security officials and eyewitnesses say Yemen's southern port city of Aden has been hit by dozens of Saudi-led coalition airstrikes.

The attacks on Saturday come as Shiite Houthi rebels mobilized hundreds of reinforcements in an effort to wrest control of the city from militias supporting embattled President Abed Rabbo Mansour Hadi.

The officials, speaking on condition of anonymity because they were not authorized to brief reporters, say fierce street battles are ongoing in the strategic Aden neighborhoods of Khour Makser and Dar Saad as the Houthis try to gain a foothold in the districts.

Hadi was forced to flee his southern stronghold of Aden last month as the Houthis advanced toward the port. The coalition of countries led by Saudi Arabia began conducting airstrikes against rebel positions on March 26.