(a) commotion

BAR.

Jeff comes out of the bathroom. Three drunk guys at a table notice the wet stain on his pants and laugh.

Up at the bar, Carl is flirting with two women when he hears (a) commotion. He turns to see: Jeff taking swings at the three drunk guys. Carl mouths '***' and excuses himself.

Hi. This is a part of a script I'm writing on. Two questions:

1) Should it be 'a commotion' or just 'commotion'? If both are OK which one would you use?

2) Is 'taking swings at' OK if Jeff is trying to punch someone more than once? Or is there a better alternative?

Thanks.