Russian officials have accused Ukraine of launching a drone attack on a building in Moscow, causing an explosion that was heard across the city’s business district.
Mayor Sergei Sobyanin said air defences had shot down the drone with its debris falling on the city’s Expo Center.
It marks the latest in a series of such attacks on the Russian capital.
Unverified footage on social media appeared to show thick grey smoke rising into the night sky over Moscow.
There was no immediate comment from Ukraine, but officials in Kyiv have never formally acknowledged launching attacks on targets in Moscow.
The attack occurred at around 04:00 local time (01:00 GMT), Russia’s defence ministry said on Telegram.
It said that, after activating the city’s air defence systems, the drone had “changed its flight path”, falling on a non-residential building on the Krasnopresnenskaya Embankment, an area of Moscow which hosts a number of government buildings.
It added that there were no initial reports of casualties.
The Expo Center is a large exhibition space used for conferences and conventions and is situated less than 5km (3.1 miles) from the Kremlin.
A witness who was in the area told Reuters news agency the attack had caused “a powerful explosion”.
The Russian defence ministry said the debris had not caused a fire, while Mr Sobyanin said the drone had caused “no significant damage” to the building.
One Russian state-owned news agency, Tass, reported that one of the outer walls of the centre had partially collapsed, citing emergency services. It said the affected area was around 30 sq m (323 sq ft).
Moscow’s Vnukovo Airport also closed following the incident, Tass said, but reopened a short time later.
Until earlier this year, Moscow remained untouched by the war in Ukraine, but in recent months has been targeted by drone strikes.
On 30 May, several buildings were reported damaged in a wave of strikes.
On 30 and 31 July, two separate drones crashed into the glass facade of a skyscraper just a few hundred metres from the Expo Center.
Ukrainian President Volodymyr Zelensky said at the time that the war was “returning to the territory of Russia” and that this was an “inevitable, natural and absolutely fair process”.
Hours before the latest strike in Moscow, a Ukrainian sea drone was destroyed during an attempted attack on Russia’s naval fleet in the Black Sea, Russia’s defence ministry said.