A Yemeni man sits beside vehicles which were allegedly destroyed by a Saudi air strike, in Sana`a, Yemen, March 26, 2015.
Seventeen people could have died so far in Yemen during the offensive of Saudi Arabia and regional allies early on Thursday, AFP reports citing civil defense sources.
Saudi forces, which some media outlets say number 100 aircraft, bombed positions of Houthi rebels in the country's capital Sanaa alongside jets from the United Arab Emirates, Bahrain, Morocco and Jordan, according to Al Arabia TV station.
Houthi Shia rebels overthrow Yemen's President in February, deepening turmoil in a country torn for years by unrest and civil war.
A Houthi spokesperson told Al Jazeera that militants deem the attack to be "a declaration of war on Yemen".
Gulf states including Saudi Arabia, Bahrain, Kuwait and Qatar earlier vowed to help Pressident Abd-Rabbu Mansour Hadi in the conflict with Houthi rebels. The government in Ryadh, which is the leading force behind the airstrikes, considers the Houthi cabinet to be "illegitimate".
The US says it does not provide direct support to the coalition, but President Barack Obama has authorized "the provision of logistical and intelligence support to GCC-led military operations".