Fighting between Armenia and Azerbaijan broke out Sunday around the separatist region of Nagorno-Karabakh and the Armenian Defense Ministry said two Azerbaijani helicopters were shot down.

Ministry spokeswoman Shushan Stepanyan also said Armenian forces hit three Azerbaijani tanks.

Nagorno-Karabakh is an ethnically Armenian enclave within Azerbaijan that has been out of Azerbaijan's control since the end of a war in 1994. Both sides have heavy military presence along a demilitarized zone separating the region from the rest of Azerbaijan.

Stepanyan said the fighting Sunday began with an Azerbaijani attack, but Azerbaijan said the Armenian side attacked and that Azerbaijan launched a counteroffensive.