Saudi Arabian security repels Houthi attack on border

On the southern border of Saudi Arabia some Yemeni Houthi rebels attacked Saudi Arabian security forces. The attack was fairly big, and Saudi forces killed up to 40 of the attackers. The Houthi rebels are Shia-Muslim, and the Yemeni government is Sunni-Muslim along with Saudi Arabia. I already explained in a previous post the relationship between Shia and Sunni, so it's obvious that the yemeni government, and Saudi Arabia would be allies. The Houthi rebels probably attacked Saudi Arabia, because they are Sunni-Muslim, and they are helping the Yemeni government.