Yep, a torn pec. Tendon detaches or snaps and the muscle just curls up into a ball. You have a pretty short time to get surgery for that kind of thing. Beyond a few days they can't stretch the muscle back to the original position so repair gets dodgy.
I had that happen to my bicep while rolling jiu-jitsu. The tear was so loud, my opponent thought I ripped his gi, I thought he broke my arm. Possibly one of the most painful things that has ever happened to me. And I went to a wine tasting later than evening LOL!