Saudi Arabia’s Civil Defence issued early warning alerts on Thursday evening for the capital, Riyadh, the southern city of Najran and the al-Kharj governorate, urging residents to take precautions over a potential threat. The alerts went out through the kingdom’s National Early Warning Platform for Emergencies.

Residents were told to stay calm, move immediately to the nearest safe place inside a building or an interior room away from windows, and remain there until the danger had passed.

Motorists who received the alert were advised to pull over safely, away from bridges and tall buildings. Emergency numbers were given as 911 for Riyadh and 998 for Najran. Authorities also warned that photographing or sharing footage of missile or drone interceptions and impact sites could carry legal consequences.

Officials had not immediately said what triggered the latest alerts. Similar warnings in recent days have been followed by announcements from the Saudi-led coalition that air defences had intercepted and destroyed Houthi ballistic missiles and drones.

Earlier on Thursday, the coalition said it had shot down a Houthi missile fired towards the Eastern Province, and a separate alert in Najran was later lifted after Civil Defence declared the danger over.

On Tuesday, alerts covering Riyadh, al-Kharj and other areas were followed by interceptions, with debris from downed missiles causing localised damage in the capital.

The alerts come as the confrontation between Saudi Arabia and Yemen’s Iran-aligned Houthis intensifies, with the coalition saying it is targeting the group’s missile network, including launch sites in Sanaa. The wider region is also on edge over the US-Israel war with Iran, now in its eighth month.

Three to four tankers were reported to have struck mines in the Strait of Hormuz on Thursday, according to Iranian accounts, while US Vice President JD Vance’s letter to Iranian security chief Mohsen Rezaei has stirred fresh talk of diplomacy.

President Donald Trump has played down the letter as outreach on medical supplies, and reports say US and Israeli officials are preparing a fresh round of strikes after next week’s US midterm elections if talks fail.