Assume a mass casualty type situation. Something along the lines of AR-558 with physical wounds ranging from phaser and disruptor hits, to concussions, broken bones, and the like.
Each Chief would be from roughly halfway through the run of their series with whatever knowledge and experience they had at that point. Each would have access to whatever kind of portable medical kit a medical officer of their time would have brought for such a situation. There are no able bodied personnel to help. No they don’t have access to a transporter.
Torres was also part of the Maquis, a severely understaffed organization, so it’s fairly likely she had to pull double duty as a medic at some point. If so, she has prior experience. O’Brien is the only other one likely to have that since he was a foot soldier for a bit.