The NSAF claims the attackers, members of the Gyumri and Etchmiadzin branches of the Yrkrapah Union, were led by Yura Aleksanyan, a leader of the Gyumri Yrkrapah group.
There are 471 polling stations throughout the 13 election precincts in Yerevan.
The number of registered voters eligible to cast ballots in the December 6 constitutional change referendum is 2,550,323.