An unknown gunman fired several gunshots from a passing vehicle at the US embassy in the Turkish capital, Ankara, on Monday, hitting a window in a security cabin but causing no casualties, police and broadcaster CNN Turk reported. The attack has coincided with a deepening row between Ankara and Washington over the trial of a U.S. pastor in Turkey.

A police officer told Reuters at the scene the drive-by shooting occurred around 5 a.m. (0200 GMT) and that nobody was hurt. The embassy was closed for a weeklong public holiday to mark the Islamic Eid al-Adha festival.

Broadcaster Haberturk showed police teams inspecting one of the entrances to the embassy and apparent damage caused by a gunshot could be seen in one window. It said empty cartridges were found at the scene.

#BREAKING: Shots fired at the US Embassy in Ankara #Turkey, targeting the security guards booth pic.twitter.com/Zg5VJHyB5M — Amichai Stein (@AmichaiStein1) August 20, 2018

Commenting on the shooting, an Erdogan spokesman said that the shooting at the US embassy was a clear attempt to create chaos.

Police teams were searching for the assailants, who fled in a white car after the attack, CNN Turk said. Four or five gunshots were heard, it said.

The U.S. embassy in Ankara and the consulate in Istanbul have been the targets of attacks by militants and have faced numerous security threats in the past.

Separately, in the latest diplomatic escalation between the US and Turkey, the WSJ reported , citing a White House official, that the Trump administration has "rejected an effort by Turkey to tie the release of a U.S. pastor with relief for a major Turkish bank facing billions of dollars in U.S. fines," and has told Ankara other issues are off the table until the minister is freed. The jailing of Andrew Brunson triggered the worst crisis between the two countries in decades and helped push the Turkish currency to record lows in recent months.

The Trump administration wants Turkey to release Brunson and other citizens it holds on disputed terrorism charges unconditionally, as well as three Turkish nationals who work for the U.S. government.

"A real NATO ally wouldn’t have arrested Brunson in the first place,” the senior White House official said, referring to Turkey’s membership in the North Atlantic Treaty Organization.

Turkey, seeking a gesture in exchange, asked the U.S. to drop an investigation into Halkbank , which is facing potentially crippling fines for allegedly violating U.S. sanctions on Iran. However, the White House official told the WSJ that the U.S. made clear to Turkey that areas of dispute between the two nations, including the fines Halkbank faces, won’t be discussed until Mr. Brunson has been released.

The U.S. and Turkey have been in prolonged negotiations over a major fine against Halkbank, but the talks stalled. Halkbank is also facing further investigation in the U.S. Halkbank recently complied with a subpoena request from the U.S. Treasury’s Office of Foreign Assets and Control, but its response was deemed insufficient, the White House official said. Washington has told Ankara that Halkbank must comply properly with the U.S. legal process before any discussions about relief could be entertained, the official said.

The Trump administration imposed sanctions against two top Turkish officials earlier this month, and Treasury Secretary Steven Mnuchin said the U.S. was prepared to take tougher steps. The rejection of a possible trade sets the stage for the U.S. to impose another round of penalties against Ankara as soon as this week.

Following the shooting, together with the WSJ report of the news of the US hardline negotiating stance, the Turkish Lira slumped against the dollar despite the weeklong Turkish holiday, and was the worst performing currency against the dollar in today's session.