The heavy bombardment came hours after the Shiite rebels, known as Houthis, aired footage on their satellite television channel purporting to show a Saudi soldier held as a prisoner of war. A top al-Qaida leader in Yemen meanwhile praised the campaign against the Houthis and called for Islamic rule in the Arab world's poorest country.
The dull thud of artillery fire rumbled across Marib but its residents, many armed with Kalashnikov assault rifles, appeared unperturbed by the nearby fighting. Many crowded a market to buy qat leaves, a mild narcotic widely consumed in Yemen.
The provincial capital is held by forces loyal to exiled President Abed Rabbo Mansour Hadi. Deputy governor Abdo Rab Ali said 80 percent of the province is controlled by pro-Hadi forces while the Houthis control the rest.
The war in Yemen pits the Saudi-led coalition against Iranian-backed Houthis and troops loyal to former President Ali Abdullah Saleh. Others opposing the Houthis include southern separatists, local and tribal militias, Sunni Islamic militants and troops loyal to Hadi.