It really depends on the movement. If they are standing fairly still, 1/60 might be OK. If they are walking it might be iffy...I'd prefer 1/90 or 1/125. If you use flash, it will help to make the images sharp because the flash burst is much shorter than the shutter.
I'm editing shots from a wedding right now, I just checked my isle shots and the one at 1/60 does have some blur in the heads & faces. My other shots are at 1/80, 1/125 & 1/160...they are very sharp.