The Subjective Agent of the Gerund

[pdh0224]

Dear teacher,


"Do you think if you're hunkered down and someone's shooting at you in your car, you're going to be able to sit there and look for Control or Alt or Function?" said Sgt. Don DeMers, president of the San Jose Police Officers' Association, the local union and the most vocal opponent of the new system. "No, you're going to look for the red button."


Q : When I first read the bold sentence, I knew "someone's" was the subjective agent of the gerund phrase 'shooting'. But Now I think " someone's " is a contracted form of "someone is".
However, my first thought also makes sense if it is in other contexts and sentences, isn't it?

[Alan]

Your first thought was right: = someone is...