The guests had taken shelter from heavy rain under a tin shack when a wall collapsed onto it in the storm.
Another 26 people were injured in the accident in Bharatpur, a district in Rajasthan state, 15 of them seriously.
“The wall and a tin shed attached to it at the marriage venue collapsed due to a storm,” police officer Anil Tank is quoted as saying.
He said the wall was nearly 90ft (27m) long and 12-13ft in height and the collapse trapped many guests.
“The injured were rushed to nearby hospitals immediately and treatment was administered,” he said.
Bharatpur district is about 200km (124 miles) south of Delhi.