Actually it happen in NCC when pastor minister, but not in big
group, considreing there might be non-believers or christian who's
frm other denomination. But during church camp, pastor was able to
minister and can see 'slain' action in big group. Pastor didn't
even touch them, cause it's the Holy Spirit in action.
Not sure how other churchs conduct, but for NCC, the ushers who
accompany the new believer are trained to 'catch' those who are
slain. Under the Spirit they will fall back. If they fall forward
the usher will catch them so they won't fall flat and got
hurt.
Under the annointing you'll never know what'll happen, i been to a
prayer meeting and saw the 'catcher' was slain together with the
one who is ministered so both fell back..