The year-long campaign of Saudi-led airstrikes in Yemen reached a new low last month with a deliberate attack on a marketplace full of civilians that killed over 100, including 25 children, and a new report has found that the bombs that did the killing came from the United States.

“The U.S. and others should pull the plug on arms to the Saudis or further share responsibility for civilian lives lost.”
—Priyanka Motaparthy,
Human Rights WatchHuman Rights Watch released the report on Thursday. Its findings detailed how the March 15 airstrike on a civilian target was made with U.S.-supplied weaponry, and renewed calls for an embargo on weapons to Saudi Arabia.

“One of the deadliest strikes against civilians in Yemen’s year-long war involved US-supplied weapons, illustrating tragically why countries should stop selling arms to Saudi Arabia,” said Priyanka Motaparthy, emergencies researcher at Human Rights Watch. “The U.S. and other coalition allies should send a clear message to Saudi Arabia that they want no part in unlawful killings of civilians.”

The rights group spoke to the airstrike’s victims and witnesses and showed footage of what it identified as U.S.-made bomb fragments:

The group “conducted on-site investigations on March 28, and found remnants at the market of a GBU-31 satellite-guided bomb, which consists of a US-supplied MK-84 2,000-pound bomb mated with a JDAM satellite guidance kit, also US-supplied,” Human Rights Watch wrote. “A team of journalists from ITV, a British news channel, visited the site on March 26, and found remnants of an MK-84 bomb paired with a Paveway laser guidance kit.”

“If confirmed, the use of 2,000-pound bombs would reflect a decision by the Saudi-led coalition that carried substantial risks for civilians,” the New York Times writes.

“The 2,000-pound general-purpose bomb, of the American standard Mark 80 series, is the largest of its class. American warplanes typically carry smaller bombs, often in the 500-pound class, in part to reduce property damage and dangers to noncombatants,” the newspaper points out.

There have been outraged calls for an embargo on weapons sales to Saudi Arabia in response to its bombing campaign in Yemen, most notably from the E.U. and the Netherlands, but the U.S. has remained silent and continued to sell weapons to the Saudis.