Two Saudi Arabian border guards were killed on Monday in an ambush in Sharoura in the far south of the country near its border with Yemen, the interior ministry said.
A ministry spokesman had no further details for the time being but that a statement would issued later in the day.
Saudi Arabia fought a brief war on its southern border with Yemen in 2009 against the country's Houthi rebel movement, which proclaims the rights of the Shi'ite Muslim Zaydi sect there.
The Sunni Muslim-ruled kingdom is also fighting an al Qaeda branch based in Yemen which has sworn to bring down the Saudi royal family.
Saudi border guards have in the past also clashed with smugglers along the long, porous desert frontier.