Answer based on context:

The first clashes between the Armenians and Azeris took place in Baku in February 1905. Soon the conflict spilled over to other parts of the Caucasus, and on August 5, 1905, the first conflict between the Armenian and Azeri population of Shusha took place. In March 1918 ethnic and religious tensions grew and the Armenian-Azeri conflict in Baku began. Musavat and Committee of Union and Progress parties were accused of Pan-Turkism by Bolsheviks and their allies. Armenian and Muslim militias engaged in armed confrontations, which resulted in heavy casualties. Many Muslims were expelled from Baku or went underground. Meanwhile, the arrest of Gen. Talyshinski, the commander of the Azerbaijani division, and some of its officers—all of whom arrived in Baku on March 9—increased anti-Soviet feelings among the city's Azeri population. On 30 March the Soviets, based on the unfounded report that the Muslim crew of the ship Evelina was armed and ready to revolt against the Soviets, disarmed the crew which tried to resist. This led to three days fighting,resulting in the death of up to 12,000 Azeris.

Which group experienced 12,000 deaths?
Azeris