Military vehicles carrying Gulf Arab soldiers arrive at Yemen’s northern province of Marib.

A Saudi Border Guard died Monday in an exchange of fire on the border with Yemen, the interior ministry said on day two of a major anti-militia offensive inside Yemen.

A post in Jazan’s Harth district came under fire from Yemen early Monday, sparking the firefight in which the soldier was killed, a ministry statement said.

The attack came as anti-militia forces backed by helicopter gunships and Gulf Arab ground troops of the Saudi-led coalition pressed their offensive in Yemen.

Coalition-supported anti-rebel forces want to push the Iran-backed Houthi militias out of Marib province and eventually move on the capital Sanaa which the rebels seized last year.

Riyadh formed the Arab alliance in March, to support exiled President Abedrabbo Mansour Hadi, in response to fears that the Houthis would take over all of Yemen and move it into the orbit of Sunni Saudi Arabia’s Shiite regional rival Iran.

At least 61 people have been killed in Saudi Arabia from shelling and skirmishes along the frontier with Yemen since the coalition campaign began.

Most of the border casualties have been soldiers.

The World Health Organization says more than 4,500 people, including a vast number of civilians, have been killed in Yemen since March 19.