Police detained a gunman who fired multiple shots near the entrance to the U.S. Embassy in Ankara, Turkey early Tuesday hours after the Russian ambassador to Turkey was killed in an attack across the street.

The state-run Anadolu news agency reported the man took out a pump-action shotgun he hid in his coat and fired around eight shots in the air before the embassy’s security guards intervened and overpowered him. The news agency reported that the man was only identified as Shain S.

The State Department said in a statement that no one was injured in the incident and praised the “prompt response” of Turkish authorities.

The embassy said its missions in Ankara, Istanbul and the southern city of Adana would be "closed for normal operations on Tuesday."

The U.S. Embassy is located just across the street from the art exhibition center where the Russian ambassador was killed. It was not immediately known if the two incidents were connected.

The leaders of Turkey and Russia have described the attack as an attempt to disrupt efforts to repair ties between their countries, which have backed opposing sides in the Syrian civil war.

It came as the foreign and defense ministers from Turkey, Iran and Russia prepared to hold a key meeting on Syria on Tuesday in Moscow.

The security scare occurred hours after the Russian ambassador to Turkey, Andrei Karlov, was shot and killed by an off-duty police officer as Karlov delivered a speech at the opening of an art exhibition in the capital.

The assassin stood over Karlov's body and condemned Russia's military role in Aleppo and elsewhere in Syria before he was killed by police.

It was not immediately clear whether Karlov's assassination and the incident at the U.S. Embassy were connected.

Two Russian news agencies, quoting unnamed sources, reported that a group of Russian investigators and experts has left for Ankara to take part in the probe, after Turkish President Recep Tayyip Erdogan said he had accepted during a telephone conversation with Russian President Vladimir Putin that Russian experts take part in the investigation.

Turkish police meanwhile detained two more people connected to Altintas on Tuesday, raising the number of people in custody for questioning to six, Anadolu reported. They include the man's parents, sister, two other relatives and his roommate in Ankara.

Turkey's pro-government newspaper Yeni Safak claimed Karlov's killing was a plot by the U.S. intelligence agency that was carried out by a movement led by U.S.-based Muslim cleric Fethullah Gulen, whom Turkey says is behind a failed coup in July aimed at toppling Erdogan. Gulen denies the accusation.

"Great Sabotage," Yeni Safak said in its headline.

The Associated Press contributed to this report.