A man wearing jeans, a T-shirt and glasses walks behind the couple and – when they reach the front row – stops and turns to a section of guests.
He mutters something to one man before lifting his top up to retrieve a handgun.
Terrified guests flee as fast as they can but he rapidly unloads the gun on them.
Ear-piercing screams echo through the church as he fires six bullets at the crowd.
He then casually strolls out of the church amid the chaos leaving the frightened guests to tend to the victims.
The incident happened in Limoeiro de Anadia in Alagoas, Brazil.
The gunman – known only as Betinho – shot two men who were to act as witnesses at the ceremony.
Cicero Barbosa da Silva, 62, and son Edmilson Bezerra da Silva, 37, were rushed to hospital by an emergency unit and are said to be in stable condition.
It is believed Betinho uttered “You hired people to kill my father” before opening fire.