Witnesses have described the aftermath of a hit-run in Melbourne's south-east that left eight people injured as being like a "bomb site" with bodies strewn across the road.

A driver who allegedly fled the scene after hitting seven children and seriously injuring a woman as they crossed a road on Friday afternoon has been arrested.

Police allege a ute struck the woman and children as they crossed the intersection of Cardinia Road and Princes Highway in Pakenham just after 3.30pm.

The scene of hit-run crash in Pakenham in which seven children and an adult were injured. Credit:Nine News

The driver left his vehicle and ran away, police allege.