The young woman was attending a wedding with several hundred others in Hanover when suddenly one of the other guests shot her several times on Sunday evening, according to police.
She was taken to hospital and later died of her injuries.
After the man shot her, police said familial fights broke out among the guests and at least four more people were injured as a result of the confrontations.
The motive behind the shooting remains unclear. Police were still collecting evidence on Monday morning.