A Saudi desalination plant was struck by a missile that appeared to come from within Yemen, according to a senior U.S. official.

It wasn’t clear if there were any casualties in the attack, the official said.

Senior officials from a range of U.S. government agencies were called back to the White House to meet Wednesday evening, the official said.

“The President has been briefed on the reports of a missile strike in the Kingdom of Saudi Arabia,” White House press secretary Sarah Sanders said Wednesday. “We are closely monitoring the situation and continuing to consult with our partners and allies.”

Saudi Arabia has led a military intervention into a prolonged bloody civil war in neighboring Yemen, and has been in conflict with Yemen’s Houthi insurgency, which is believed to be backed by Iran.