An Iraqi official says an airstrike north of Baghdad has hit two cars carrying members of Iran-backed militia, one day after a U.S. airstrike killed top Iranian Gen. Qassem Soleimani. The official said five members of the militia were killed.

The official spoke on condition of anonymity because they was not authorized to talk to reporters.

The Iran-backed Popular Mobilization Forces confirmed the strike, saying it targeted one of its medical convoys near the stadium in Taji, north of Baghdad. The group denied any of its top leaders were killed.

The American military did not carry out the reported attack, according to a U.S. official who spoke on condition of anonymity.

The death of Soleimani, the head of Iran's elite Quds Force, marks a major escalation in the standoff between Washington and Iran, which has careened from one crisis to another since U.S. President Donald Trump withdrew from the 2015 nuclear deal and imposed crippling sanctions.

The targeted strike against Soleimani and any retaliation by Iran could ignite a conflict that engulfs the whole region, endangering U.S. troops in Iraq, Syria and beyond. Over the last two decades, Soleimani had assembled a network of heavily armed allies stretching all the way to southern Lebanon, on Israel's doorstep.

The United States said it was sending nearly 3,000 more troops to the Middle East, reflecting concern about potential Iranian retaliation. The U.S. also urged Americans to leave Iraq immediately following the airstrike at Baghdad's international airport that Iran's state TV said killed Soleimani and nine others.

The announcement about sending more troops came as Trump said Soleimani's killing was not an effort to begin a conflict with Iran.

"We took action last night to stop a war. We did not take action to start a war," Trump said, adding that he does not seek regime change in Iran.

Iran's supreme leader, Ayatollah Ali Khamenei, vowed "harsh retaliation" after the airstrike, calling Soleimani the "international face of resistance." Khamenei declared three days of public mourning and appointed Maj. Gen. Esmail Ghaani, Soleimani's deputy, to replace him as head of the Quds Force.