Twin sisters in Brazil have reportedly been fatally shot in the back of their heads in a horrific gang-related double execution that was livestreamed on Instagram.

The 18-year-olds — both mothers named locally as Amália and Amanda Alves — were forced to kneel before being killed because they knew too much about a drug deal, the Sun reported, citing local media.

The shocking footage of the murders behind a complex in Pacajus in the northeast state of Ceara has been viewed thousands of times, according to Brazilian news outlets.

A 17-year-old boy has been arrested on suspicion of murder and was being questioned by authorities.

The teens were forced to lift up their hair into a bun before they were executed, the Sun reported, citing Jornal de Brasília.

The suspect allegedly fired two more rounds at one of the sisters before blasting another four bullets at the other’s body.

Amália left behind a 6-month-old son, while her sister is survived by a 3-year-old daughter, the Sun reported.