Rear ended tonight, sputtering sound coming from front of car?

i was stopped at a light when i was rearended tonight, this girl hit the car behind me, wich hit my car, as soon as it happened i heard this sound, kinda like sputtering, i noticed it was coming from the front over by the drivers tire, (in that area) went on for 4-5 minutes then just stopped. i left my car running the whole time, about 20-30 minutes, never overheated, drove home the 10 or so blocks, seemed fine, starts back up fine. any ideas what was making this noise?