The pair died when three areas in the mountainous Jazan region were inundated by flood waters, Al-Ekhbaria news channel reported on its Twitter feed.
Citing the civil defence agency, it said six other people were injured and 18 rescued in the region, which borders Yemen.
Flooding brings Qatar to near standstill
Heavy rains have struck Saudi Arabia this week, including in the desert capital Riyadh where schools closed on Wednesday after floods caused traffic chaos during a severe storm.
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