The fighting between Armenian and Azerbaijan grew out of control on the border of Artsakh.
Azerbaijani President Ilham Aliyev vows to avenge blood of martyrs, accuses Armenia of killing civilians.
Fighting between Azerbaijan and Armenia broke out around the disputed region of Nagorno-Karabakh after Armenia attacked civilian settlements and military positions, Azerbaijan President says.
President Ilham Aliyev in his address to the nation said Armenian armed forces fired on Azerbaijani settlements and military positions from several directions, using various types of weaponry, including heavy artillery.
"As a result of the enemy fire, there are casualties among the civilian population and our servicemen. Some people have been wounded. May Allah rest our martyrs in peace," he said, without mentioning any specific numbers on casualties.
Aliyev vowed to avenge the blood of martyrs, saying the Azerbaijani army continues retaliation on Armenian military positions, and that many units of its military equipment have been destroyed.
"This is another manifestation of Armenian fascism," he said.
The Azerbaijani leader added that besides the attacks, Armenia continues its illegal settlements in Azerbaijani territories.
"Azerbaijan defends its lands, Upper Karabakh belongs to Azerbaijan," Aliyev asserted.
( ARMENIA DECLARES MARTIAL LAW)
Meanwhile Armenia's Defence Ministry said its troops downed two Azerbaijani helicopters and three drones in the clashes.
The ministry said the downed helicopter's crew had survived.
Armenian Prime Minister Nikol Pashinyan said on Sunday that his country declared martial law and total military mobilisation following clashes.