Air strikes on so-called Islamic State's Syrian stronghold of Raqqa have cut the city's water supply, with 20 civilians reported dead.
The anti-IS group Raqqa is Being Slaughtered Silently said a water pumping station had been hit, along with the Taj Hall and Furousiya area.
IS-linked news agency Amaq also said Raqqa's water supply had been cut.
Russia said its bombers had targeted an arms depot, a chemical weapons factory and a training camp.
A defence ministry statement said the strikes had inflicted "significant damage" and that a large number of militants had been killed.
Raqqa is Being Slaughtered Silently (RBSS), whose activists have reported on developments on the ground in Raqqa since IS militants seized control of the city in early 2014, said the water pumping station hit in Thursday's strikes was located in the nearby village of Kasrat.
Residents found their water had been cut off "totally" afterwards, it added.
Amaq also reported the "interruption of the water supply in all neighbourhoods".
RBSS said 20 civilians had been killed and 50 others wounded in the air strikes, but the UK-based Syrian Observatory for Human Rights put the death toll higher.
It said 24 civilians had died, along with six others whose identities could not yet be confirmed.
Raqqa, estimated to have a population of between 250,000 and 500,000, has become the de facto capital of the "caliphate" whose creation was proclaimed by IS two years ago after it took control of large swathes of territory in Syria and Iraq.
IS militants are currently under pressure from two separate offensives west and north-west of Raqqa by Russian-backed Syrian government forces and an alliance of Kurdish and Arab fighters supported by the US.