BEIRUT — American fighter aircraft approached an Iranian passenger plane over Syria on Thursday, a U.S. military official said, an incident that Iranian media said prompted the pilot to abruptly drop altitude and triggered panic aboard.

Iran’s Fars News and the state-run Syrian Arab News Agency reported that the Iranian Mahan Air plane was flying above the Tanf area of eastern Syria, where a U.S. military base is located, when two jets approached, identifying themselves by radio as American. The pilot responded by dropping the aircraft to avoid collision, the official Islamic Republic of Iran Broadcasting news agency said.

Videos circulating on social media showed Arabic and Farsi speakers aboard the plane, some of them suffering injuries. One video showed the plane seemingly suddenly dropping as women screamed in the background. Another featured a Farsi-speaking man who suffered a head injury that marked his face with a thin line of blood.

Capt. Bill Urban, a spokesman for U.S. Central Command, said that an American F-15 jet was on a “routine air mission” near the Tanf garrison, an isolated outpost, when it “conducted a standard visual inspection of a Mahan Air passenger airliner at a safe distance of approximately 1,000 meters from the airliner.”

“Once the F-15 pilot identified the aircraft as a Mahan Air passenger plane, the F-15 safely opened distance from the aircraft. The professional intercept was conducted in accordance with international standards,” Urban said in a statement.

A defense official, who spoke on the condition of anonymity to discuss a sensitive incident, said a second U.S. aircraft was also in the vicinity. The official said it was possible that the proximity of the U.S. jet, while far enough away for its pilot to freely maneuver around the slower commercial aircraft, may have triggered an audio collision alarm in the passenger plane’s cockpit.

The plane, bound from Tehran to the Lebanese capital of Beirut, landed at its destination. The Lebanese Red Cross told The Washington Post it had reported to the scene but had not yet evacuated anyone who was injured.

An Islamic Republic of Iran Broadcasting reporter, who appeared to have been aboard the flight, said from Beirut that three passengers were wounded during the fighter jets’ “intentional move.”

In another video that appears online, a woman filmed the plane aisle, the floor strewn with papers and packaged items, with passengers sporting bright-yellow life vests. One child had gauze wrapped around his head. “I’m filming what happened, yeah, in case we die,” she said in Arabic.

Fars News later reported that the plane was back in Iran, apparently without any more incidents.

The incident comes amid heightened tensions between Washington and Tehran. The Trump administration has identified Iran as its chief adversary in the Middle East, authorizing economic sanctions and taking steps designed to curb the country’s support for armed groups beyond Iran’s borders.

Early this year, the two countries appeared to reach the brink of war after a U.S. drone killed a revered Iranian military leader, Qasem Soleimani, in Baghdad. Iran responded by firing missiles at a base housing U.S. troops in Iraq.

Around the same time, Iranian air defenses mistakenly shot down a Ukrainian airliner taking off from Tehran’s international airport, an incident that Iranian officials later said was due to an error with an air defense radar as the country prepared for a possible American counterstrike.

The two countries are also at odds in Syria, where Iranian backing is a lifeline for President Bashar al-Assad and where the United States has carved out its own area of influence in other parts of the country as part of its mission against the Islamic State.

The U.S. military maintains a 30-mile air and ground exclusion zone around the Tanf base, which was established to battle the Islamic State but which now forms part of the American strategy to limit Iran’s expansion in Syria. The base sits along a highway connecting Damascus to Baghdad and Tehran to the east.

In the past, U.S. forces have shot down several Iranian drones and fired on Iranian-linked forces when they ventured within the zone around the base.

Iranian Foreign Ministry spokesman Abbas Mousavi said U.N. Secretary General António Guterres had been informed of the incident, which was under investigation.

Ryan reported from Washington.