Saudi Arabia said on Wednesday that an attack on an Aramco building in the kingdom's east sparked a "limited fire" and that debris from intercepted Houthi missiles wounded four people in the capital Riyadh.
It came hours after the Saudi-led coalition battling Yemen's Houthis said it had intercepted several missiles on Tuesday evening, including over Riyadh.
A Saudi energy ministry official said an administrative building belonging to oil giant Aramco in Dhahran was struck on Tuesday evening, resulting in a "limited fire" but "no casualties or fatalities".
Saudi Arabia's civil defence agency said on Wednesday that four people -- two women, a man and a child -- were wounded by debris from two intercepted Houthi cruise missiles in the capital and that 15 homes were damaged.
Earlier on Tuesday, the coalition struck oil sites across western Yemen, in response to the deadliest attack on the kingdom's soil in years.
The strikes in Yemen's Sanaa and the western provinces of Dhamar and Saada targeted facilities used to "supply the war effort" by the Houthis to "threaten the kingdom, Yemen, the southern Red Sea and waterways", coalition spokesman Turki al-Maliki wrote on X.
A powerful explosion then rang out in the Saudi capital, with a phone alert sent to residents saying "the city of Riyadh is facing a hostile aerial threat".
While walking down a major avenue in Riyadh, a witness told AFP he "saw a projectile cutting across the sky" above a mall, saying it left "a yellowish trail of light followed by a trail of smoke. Then, we heard an explosion".
"People were calm; no one was speaking. We were scared and all looking up at the sky," he added, requesting anonymity.
After Houthi strikes on Saudi airports and energy sites in recent days, the coalition issued its first evacuation order in the Yemeni capital since the war flared in July, before attacking the Yemen Petroleum Company facility on Sanaa's outskirts.
An AFP correspondent in Sanaa reported an explosion, while a breaking news alert on the Houthi-affiliated Al-Masirah TV channel said "Saudi aggression" targeted the oil firm.
- Renewed threats -
A strike on Riyadh's international airport on Saturday left 13 people dead and operations suspended in the worst attack since 2015.
The Saudi cabinet vowed in a meeting earlier Tuesday, led by Crown Prince Mohammed bin Salman, that it "will not allow its security or freedom of navigation in the Red Sea and Bab al-Mandab Strait to be threatened".
An AFP correspondent reported that many civilians in Sanaa, fearing shortages, rushed to queue in front of fuel stations after the coalition warning.
The Houthis had earlier issued a new threat to target Riyadh's international airport, a refinery, and an Aramco facility in Dammam if the strike went ahead, calling for citizens to avoid them.
Many countries have issued travel warnings to their citizens in Saudi Arabia, most recently France, which told its citizens to avoid Riyadh, Jeddah and Dammam airports.
The Saudi-led coalition has supported Yemen's government militarily against the Houthis since 2015 in a long-running civil war that has created a dire humanitarian crisis.
- Economic woes -
Traffic in perennially gridlocked Riyadh was noticeably lighter this week as remote learning for all schools and work-from-home orders for some companies took effect, according to AFP journalists.
Saudi Arabia faces a major economic contraction this year, with GDP expected to shrink 3.3 percent, the International Monetary Fund said on Tuesday, predicting a regional drop over Iran's blockade of the Strait of Hormuz.
The kingdom was already facing headwinds from Iran's chokehold on the Hormuz strait since the start of the Middle East war in February, when the US and Israel attacked Iran.
But the restart in July of Yemen's frozen war has further roiled the kingdom and brought the fight to its own soil.
Houthi attacks have also targeted oil tankers in the Red Sea -- Saudi Arabia's alternative export route.
In Yemen, the renewed fighting was fuelling the risk of infectious disease outbreaks.
Suspected cholera cases tripled there in three weeks, the World Health Organization said Tuesday, warning that the growing disease burden was straining hospitals already treating war casualties.
- 'Behaving very badly' -
The Riyadh airport attack had prompted US President Donald Trump to say he was considering joining Saudi strikes against the Houthis.
He wrote on his Truth Social platform on Tuesday that "the Houthis are behaving very badly", accusing them of acting "probably at the behest of Iran".
"I'll be there after the elections, and I will never forget!" he wrote, referring to next month's midterms.
The Houthis warned the US against intervention, with political bureau member Mohammed Al Bukhaiti telling AFP they would target American interests in the region.
Bukhaiti said the purpose of the campaign against Saudi targets was to send a message to the crown prince "that he can no longer wage aggression against Yemen from a safe position".