Ty Montgomery left Thursday night’s Bears-Packers game in the first quarter, and some additional details as to why emerged after the rain delay.

The Packers running back suffered broken ribs, inducing the locker room trip, Ian Rapoport of NFL.com tweets. The fractures occurred early, but the third-year performer attempted to play through the injury, Rapoport reports. He will not return to the game.

Green Bay’s carrying virtually no experience at running back behind Montgomery, himself drafted to play wide receiver.