Ten people were killed and at least four were injured after drug traffickers fired machine guns and tossed grenades at an Independence Day party early Saturday.

What started Friday evening as a holiday dance in Turano Hill, a Rio shantytown, turned into a massacre after midnight when about 30 men arrived and started firing into the crowd of about 400 people.

The invaders dragged nine corpses through the shantytown’s streets and loaded them into two cars that were parked about five miles from the scene of the massacre.

Police recovered the nine bodies and found a 10th body full of bullet holes near the massacre scene.