A shoot-out has erupted at a shopping mall in the centre of Donetsk, the Ukrainian stronghold of pro-Russia rebels, according to reports.
A Reuters reporter said up to six rebel gunmen were hiding behind cars in the mall's car park, firing at another group of people.
It comes as Russian president Vladimir Putin has agreed to meet Ukrainian president Petro Poroshenko on August 26, along with representatives from the European commission and the Eurasian Customers Union.
Poroshenko confirmed that "stabilising the situation" in eastern Ukraine would be on the agenda.
More than 2,000 people have died in clashes between the pro-Moscow rebels and forces from Kiev.