Reuters cited Russian state news agency TASS reporting on an incident in which a vehicle crashed into the gate of the Russian Embassy building in the Romanian capital city of Bucharest at around 6:30 a.m. Wednesday morning.
A Radio Romania report was quoted as saying that the car caught fire following the crash.
TASS said the driver was killed on impact.
Romanian police are investigating the incident and traffic has been closed off near the embassy building.
On Monday, US President Joe Biden called Russian President Vladimir Putin a "war criminal" and called for him to be put on trial following reports of mass graves in Bucha.
Germany, France, Britain, the US, and the European Union condemned Russia following the discoveries, with France, Britain, and Germany calling for a war crimes investigation and Reuters reported that the United States would ask the UN General Assembly to suspend Russia from the Human Rights Council.
“He is a war criminal,” Biden told reporters. “This guy is brutal, and what’s happening in Bucha is outrageous and everyone’s seen it."
“I think it is a war crime," he added. "He should be held accountable.”
Biden's comments and a row of other condemnations follows accusations that Russian troops killed dozens of civilians in the town of Bucha as they fled the Kyiv region.
Since Russia's invasion of Ukraine began on February 24, the General Assembly has adopted two resolutions denouncing Russia with 140 voting in favor.
The U.S. has asked the UN General Assembly to suspend Russia from the Human Rights Council.
"My message to those 140 countries who have courageously stood together is: the images out of Bucha and devastation across Ukraine require us to now match our words with action," US ambassador to the UN Thomas-Greenfield said on Monday.
Vassily Nebenzia, Russia's ambassador to the United Nations, labeled the attempted ouster of his country from the council as "unbelievable", stressing that it wouldn't aid peace talks with Ukraine.