If student/s from Government recognized collages, and respective collage given letter for internship, then it will not attract PF/ESI. If student/s from private collage than you have to deduct their PF/ESI.
If you are not deducting ESI, then take EC / WC (workman's compensation) policy as suggested by Mr. S K Bandyopadhyay.
It is strongly recommended that you to check and confirm the above and take decision.