Saudi Arabia's landmark Kingdom Centre skyscraper in Riyadh ordered office employees to work remotely on Sunday as Houthi attacks continued across the kingdom, while two Saudi helicopter pilots died in a crash near the Yemeni border.
The developments come amid renewed fighting between the Saudi-led coalition and Yemen's Iran-backed Houthis, with escalating attacks threatening infrastructure and regional shipping routes.
Management of the 99-storey Kingdom Centre made remote working mandatory until further notice without specifying a reason.
The directive follows a Houthi attack on Riyadh's King Khalid International Airport a week earlier that killed 13 people.
The skyscraper houses offices belonging to Merrill Lynch, McKinsey and the International Monetary Fund, although its shopping mall remains open.
Schools have also extended remote learning arrangements, while Riyadh's international airport remains closed.
The Saudi-led coalition reported intercepting two drones near Riyadh, another over the Eastern Province and two ballistic missiles in southern Saudi Arabia.
Authorities had previously issued a threat alert in the capital.
The coalition confirmed that two officers died when an AH-6i reconnaissance helicopter crashed in Najran, attributing the incident to a technical malfunction.
Houthi spokesman Yahya Saree separately claimed the group had shot down a Saudi Apache helicopter in the same region.
The conflicting accounts emerged as fighting intensified following an uneasy four-year truce.
Last month, Houthi forces captured strategic territory along Yemen's Red Sea coast, including areas around the Bab al-Mandab strait.
The Houthis have targeted Saudi oil facilities, tankers and aviation infrastructure, while coalition aircraft have conducted repeated strikes in Yemen.
On Saturday, the Houthis reported that Saudi airstrikes killed 12 people, including three children.
The group has also declared a maritime blockade against Saudi Arabia, threatening a crucial oil export route following Iran's blockade of the Strait of Hormuz.
Meanwhile, Egypt's parliament was scheduled to convene an emergency session on Sunday after President Abdel Fattah al-Sisi requested authorization to support Saudi Arabia's defense.
Sisi emphasized that any Egyptian involvement would be defensive rather than offensive.