People look at a building damaged by an air strike on a nearby Scud missile base in Yemen's capital Sanaa April 20, 2015. [Photo/Agencies]

SANAA -- At least 60 people were killed and 49 others wounded in Yemen's capital of Sanaa on Monday morning in one of the fiercest air raids by Saudi-led coalition forces that began more than three weeks ago.

At least 60 Houthi fighters and soldiers of the former republican guards loyal to former president Ali Abdullash Saleh were killed in a military base, on Attan mountain in southwestern Sanaa, during the airstrikes on Monday morning, a security source told Xinhua on condition of anonymity.

The air raids hit the missile base and caused one of the most powerful explosions since the strikes began on March 26, the source said.

Windows of many residential houses near the base was smashed and at least 49 people were wounded, the source added.

Witnesses said about two dozen ambulances were rushing to the military base, and explosions could still be heard after the warplanes left.

The air raids have forced hundreds of thousands of people to flee the capital and several other major cities to seek shelter in villages that have few military targets.

The Saudi army were shelling the Shiite Houthi group in the northern border regions and tribal forces loyal to exiled President Abd-Rabbu Mansour Hadi were battling the Houthi fighters in northern provinces.

The airstrikes and battles on the ground have killed about 700 people and wounded 3,000, according to reports from the Yemeni health and interior ministries.

The three-week airstrikes on Yemen have caused a humanitarian disaster in the Arab country.

Fuel and electricity supply have been cut off for almost a week in Sanaa, Aden and Taiz, the three major cities in the country, where a large number of people do not have access to drinking water.