TEHRAN, Iran (AP) — Iran says it has launched “tens” of surface-to-surface missiles at Iraq’s Ain Assad air base housing U.S. troops over America’s killing of a top Iranian general.

State TV described it early Wednesday as Tehran’s revenge operation over the killing of Revolutionary Guard Gen. Qassem Soleimani.

U.S. forces could not be immediately reached for comment. White House press secretary Stephanie Grisham said the White House is aware of the reports.

“The President has been briefed and is monitoring the situation closely and consulting with his national security team,” she said.

Ain Assad air base is in Iraq’s western Anbar province. It was first used by American forces after the 2003 U.S.-led invasion that toppled dictator Saddam Hussein. It later saw American troops stationed there amid the fight against the Islamic State group in Iraq and Syria.

State TV said the operation’s name was “Martyr Soleimani.” It said the Guard’s aerospace division that controls Iran’s missile program launched the attack. Iran said it would release more information later.

A stampede broke out Tuesday at the funeral for a top Iranian general slain in a U.S. airstrike, and at least 56 people were killed and more than 200 were injured as thousands thronged the procession, Iranian news reports said.

As the crowds mourned Revolutionary Guard Gen. Qassem Soleimani, more angry calls rose from Iran to avenge his death, drastically raising tensions in the Middle East.

The U.S. continued to reinforce its own positions in the region and warned of an unspecified threat to shipping from Iran in the region’s waterways, crucial routes for global energy supplies. U.S. embassies and consulates from Asia to Africa and Europe issued security alerts for Americans. The U.S. Air Force launched a drill with 52 fighter jets in Utah, just days after President Donald Trump threatened to hit 52 sites in Iran.

Tuesday’s deadly stampede took place in Soleimani’s hometown of Kerman as his coffin was being borne through the city in southeastern Iran, said Pirhossein Koulivand, head of Iran’s emergency medical services.

There was no information about what set off the crush in the packed streets, and online videos showed only its aftermath: people lying apparently lifeless, their faces covered by clothing, emergency crews performing CPR on the fallen, and onlookers wailing and crying out to God.

“Unfortunately as a result of the stampede, some of our compatriots have been injured and some have been killed during the funeral processions,” Koulivand said, and state TV quoted him as saying that 56 had died and 213 had been injured.

Soleimani’s burial was delayed, with no new time given, because of concerns about the huge crowd at the cemetery, the semi-official ISNA news agency said.

A procession in Tehran on Monday drew over 1 million people in the Iranian capital, crowding both main avenues and side streets in Tehran. Such mass crowds can prove dangerous. A smaller stampede at the 1989 funeral for Ayatollah Ruhollah Khomeini killed at least eight people and injured hundreds.

Hossein Salami, Soleimani’s successor as leader of the Revolutionary Guard, addressed a crowd of supporters gathered at the coffin in a central square in Kernan. He vowed to avenge Soleimani, who was killed in a U.S. drone strike Friday near Baghdad’s airport.

“We tell our enemies that we will retaliate but if they take another action we will set ablaze the places that they like and are passionate about,” Salami said.