Updated

Strong shelling has hit both government- and rebel-controlled areas of eastern Ukraine, continuing an escalation of fighting this week. Ukraine says four soldiers had been killed over the past day.

Russian Foreign Ministry spokeswoman Maria Zakharova said Friday that several civilians were killed in the city of Donetsk, the main stronghold of Russian-backed separatist rebels, but did not give details.

Shelling from the rebel side has centered on the town of Avdiivka, just north of Donetsk city. A British photographer was wounded in the eye in shelling Thursday night, according to the Facebook page of Ukraine's anti-rebel military operation.

At least 15 people have been reported killed in the fighting this week. More than 9,700 people have died in the war between government troops and rebels that began in April 2014.