Story highlights Azerbaijani helicopter involved in striking Armenian forces is shot down, Azerbaijani state media reports

Azerbaijani official says that "Armenia bears responsibility" for the latest violence

Armenia's Defense Ministry blames the Azerbaijanis for their "aggressive and irresponsible decisions"

(CNN) Long-simmering tensions between Armenia and Azerbaijan flared again Saturday, with at least 18 Armenian and 12 Azerbaijani troops killed in fighting, according to state media reports.

The violence was centered in Nagorno-Karabakh, a region occupied by Armenian forces but surrounded and claimed by Azerbaijan. Where it belongs has been in dispute for years, though it's been relatively rare of late for this discord to erupt in bloodshed.

That's what happened Friday night and Saturday. An Azerbaijani Mi-24 helicopter carrying out airstrikes on Armenian military positions was shot down, and a mine blast damaged a tank, according to Azerbaijan's official Azertac news agency.

The same report said that six Armenian tanks and 15 artillery pieces were destroyed, while over "100 enemy soldiers were killed and injured."

The Armenpress news agency , citing President Serzh Sargsyan, said 18 troops were killed and 35 wounded "because of the provocative actions made by the Azerbaijani armed forces along the entire length of contact line with the Nagorno-Karabakh Republic."

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