The latest battle between Azerbaijan and Armenia has caused casualties on both sides.
The clash erupted on the border on Tuesday. The countries said on Wednesday that seven Azerbaijani servicemen were killed and 10 others were wounded, while on the Armenian side, one was killed, 13 were captured and 24 were unaccounted for.
Russia's Defense Ministry says fighting has subsided with the country's mediation.
The European Union said on Wednesday in a statement that it is deeply concerned about the violence. It also said European Council President Charles Michel called on the countries to de-escalate the situation and honor a ceasefire.
Azerbaijan and Armenia have long been at loggerheads over the disputed Nagorno-Karabakh region. The conflict intensified last year, killing several thousand people.
After a ceasefire agreement in November last year, both sides accused each other of staging attacks in breach of the deal.