A spokesperson said investigators had yet to establish why the fireworks, which were being stored under the stage at Vilnius' largest open air venue, ignited on the morning of Nov. 20.
When the alarm was raised, 12 fire trucks rushed to the scene. It took an hour to bring the ensuing blaze under control.
The dead man was a park service employee, said the spokesperson. Two of his colleagues sustained minor injuries.
The Vingis Park stage last caught fire in August, when a natural gas flame - the center piece of anniversary celebrations being staged by the state gas utility Lietuvos Dujos - got out of control.