According to Armenian Prime Minister Nikol Pasjinian, Azerbaijan has carried out large-scale attacks on communities in Nagorno-Karabakh.
Pasjinian says Armenian forces responded by shooting down two helicopters and three drones.
According to the Nagorno-Karabakh government, a number of civilian lives have been claimed.
Strained relationship
In July, 15-20 Armenian and Azerbaijani soldiers were killed in fighting.
Relations between the two countries have been strained since they became independent in connection with the collapse of the Soviet Union.
During the years around 1990, a war was fought over the Nagorno-Karabakh region, which is located in Azerbaijan but has an Armenian population majority.