A missile strike on Riyadh’s King Khalid International Airport killed at least 12 people and injured 309 on Saturday, Saudi civil aviation authorities said. Airport operations remained suspended Sunday, and some of the wounded were in critical condition.

The dead included one American and four Saudi citizens, as well as nationals of Bangladesh, Egypt, Jordan, Palestine, Syria and Sudan. Saudi Arabia, its allies and Washington blamed the Iran-backed Houthis, but the group had not immediately claimed responsibility. It renewed a warning to stay away from Saudi airports.

President Donald Trump said Saturday that the United States was considering joining Saudi military operations against the Houthis. The strike followed other attacks on the airport during the past week, including one Thursday that killed three people, as fighting between the Houthis and a Saudi-led coalition has resumed.