I not only assume the bait fish are being attacked I can see they are. A screenshot only shows the instant it is taken. Stuff goes on continuously, it is sort of obvious.
The only way to know specifically what the preditor/s is involves a catch or knowing what is in the body of water you see it happening.
Being familiar with species, their likely locations, and how they relate to their food also will give you a clue to what they are.
If you have Humminbird equipment like I do, you can use the FishID to show the larger preditors, like I did in the second, third, and fourth, screen shots. Other mfg do not have that feature to only assign the fish symbols based on air bladder sizes. Small bass will not get the symbols, neither will bushes, trees, or suspended matter. If you see the FishID symbols in crappie schools, those are NICE ones.
Refer to the Screenshots topic above for more examples.