The promotional balloons were decorated with the governing party's election slogan "Let's believe in change".
The emergencies ministry said 144 people suffered burns when scores of balloons burst into flames at a concert staged by President Serzh Sarkisian's Republican party in Yerevan's central Republic Square.
"The balloons exploded and caught fire after people holding the bunches released them from their hands into the air," a witness told AFP.
It was not immediately clear what caused the explosions although police said they were looking into various potential reasons including the "improper storage of flammable substances".
E.g.... inside balloons.