Dozens of people were killed in an attack on a migrant facility in Houthi-controlled northern Yemen, the Iran-backed militia and aid officials said on Monday.

The Houthi militia said that an American strike hit what they called a migrant center in Saada, killing at least 68 African migrants. The U.S. military did not immediately respond to a request for comment about the claim.

The attack came hours after the U.S. military said that American forces had conducted more than 800 strikes in Yemen since mid-March in a campaign against the Houthis. It said the campaign targeted “multiple command-and-control facilities, air defense systems, advanced weapons manufacturing facilities and advanced weapons storage locations” — but made no mention of civilian casualties.