(CNN)Long-simmering tensions between Armenia and Azerbaijan appear to have flared up in the contested Nagorno-Karabakh region, with both sides accusing each other of attacking civilians amid reports of casualties.
Clashes break out between Armenia and Azerbaijan over disputed region
The neighboring former Soviet republics have long been at odds over the territory -- which is situated within the borders of Azerbaijan -- and fought a war over it that finished in 1994.
Despite the conflict ending with a Russian-brokered ceasefire, military skirmishes between the two sides are not uncommon.
While Armenia said it was responding to missile attacks launched by its neighbor Sunday, Azerbaijan blamed Armenia for the clashes.
In response to the alleged firing of projectiles by Azerbaijan, Armenian Prime Minister Nikol Pashinyan tweeted that his country had "shot down 2 helicopters & 3 UAVs, destroyed 3 tanks."
Arayik Harutyunyan, leader of the self-proclaimed Republic of Artsakh, a de facto independent Armenian state not recognized internationally which controls Nagorno-Karabakh, said the region had lost positions to Azerbaijan.
"We have lost some positions. Mostly in the direction of Talysh and in the southern parts," Harutyunyan said during a press conference Sunday.
As a result of the escalating tensions, the Armenian government has decided to impose martial law and to order "general mobilization," Pashinyan said in a later tweet.
Azerbaijan's parliament on Sunday voted to impose martial law, effective as of midnight (4 p.m. ET), and President Ilham Aliyev approved the decision.
Armenia earlier claimed that its neighbor had targeted civilians in peaceful areas, including in Stepanakert, the region's capital.
Artak Beglaryan, an Artsakh official Artsakh, said in a tweet that a mother and child had been killed.
Beglaryan also said dozens of people had been wounded and large infrastructural damage had been caused, adding: "Azerbaijan is intentionally targeting civilian objects."
However, Azerbaijan suggested Armenia was accountable for the latest flare-up between the two countries.
Hikmet Hajiyev, assistant of the President of the Republic of Azerbaijan and head of the Foreign Policy Affairs Department of the presidential administration, tweeted Sunday: "There are reports of dead and wounded among civilians and military servicemen. Extensive damage has been inflicted on many homes and civilian infrastructure."