ADEN, Yemen, May 7 (Xinhua) -- Mortar shells fired by the Shiite Houthi fighters hit civilian targets in Yemen's central province of al-Bayda on Monday, killing five people and injuring several others, a military official told Xinhua.

"Houses located in Qaniah district of al-Bayda province were targeted with a number of mortar shells fired from Houthi-controlled areas," the local military official said on condition of anonymity.

"Some of the shells randomly hit houses and killed five people including women and caused injuries to several others," the local source said.

The Houthis usually target areas controlled by the government with artillery and mortar shellings in revenge for losing areas during ground fighting, according to the official.

A tribal source told Xinhua by phone saying that "Houthis booby-trapped and then detonated five houses belonging to people linked with army commanders of the Saudi-backed Yemeni forces in al-Bayda province."

Meanwhile, the Yemeni government forces and its allied fighters engaged in fierce battles with Houthis in different areas of Yemen, mainly in the western coast part of the country.

Local residents said that intense fighting coordinated with intensified Saudi-led airstrikes is still ongoing in areas between Taiz and al-Hodeidah port city.

They said that the pro-government forces made broad advances and gained control over the Houthi supply lines leading to Taiz province.

The impoverished Arab country has been locked into a civil war since the Iranian-backed Shiite Houthi rebels overran much of the country militarily and seized all northern provinces, including capital Sanaa, in 2014.

Saudi Arabia leads an Arab military coalition that intervened in Yemen in 2015 to support the government of President Abd-Rabbu Mansour Hadi after Iran-backed Houthi rebels forced him into exile.

The United Nations has listed Yemen as the world's number one humanitarian crisis, with seven million Yemenis on the brink of famine and cholera causing more than 2,000 deaths.?