Saudi Arabia intercepted three missiles and three drones fired by Houthi rebels in neighbouring Yemen.
One was destroyed in the eastern city of Dammam, where falling shrapnel injured two children and damaged buildings, the defence ministry said.
The Houthis said they had targeted Saudi oil facilities.
The other attacks were aimed at oil sites in the southern provinces of Jizan and Najran, the group said.
There are no immediate reports of impact on Saudi oil facilities.
In 2019, the rebels claimed responsibility for a drone attack on two facilities run by Saudi state-owned oil company Aramco. It temporarily reduced crude oil production by half the Kingdom’s output at that time.
Saudi Arabia entered the Yemen war in 2015, on the side of the internationally recognised government, shortly after the Houthis seized the capital, Sanaa.
The UN has called the civil war there the world’s worst humanitarian crisis. As of March 2020, it had verified the deaths of at least 7,700 civilians, most caused by Saudi-led coalition air strikes.
Monitoring groups believe the true death toll is far higher, however. The US-based Armed Conflict Location and Event Data Project (ACLED) said in October 2019 that it had recorded more than 100,000 fatalities, including 12,000 civilians killed in direct attacks.