The accident took place in Sakara police station area at about 2 AM.
Five people were killed on the spot, while two others succumbed to injuries while undergoing treatment at a hospital, Deputy Superintendent of Police, Muzaffarpur (East), Gaurav Pandey, said.
He said seven people who were injured in the accident were admitted to a hospital.
The accident victims were returning from Tajpur, Samastipur district, where they had gone to attend a wedding, Pandey said.