Cleveland Browns quarterback Brian Hoyer is believed to have suffered a torn anterior cruciate ligament (ACL) in his right knee. This report comes from NFL insider Adam Caplan.

Early word on Brian Hoyer's knee injury is ACL tear, source said. But MRI results are not available yet. — Adam Caplan (@caplannfl) October 4, 2013

Hoyer left Thursday night’s game early in the first half after a first-down run led to the quarterback sliding awkwardly and sustaining a hit that led to his right knee being twisted. The Browns ultimately beat the Buffalo Bills 37-24, but—assuming the news is confirmed via an MRI—the storybook season of a Cleveland native leading the Browns will have an unfortunate ending.

[Related: Browns beat Bills despite losing Hoyer]