Everything is basically being compressed into a singularity though, so it's a lot of matter being compressed into an extremely small space all at the same time. The gravitational force is huge.
As explained in the wiki link:
Yeah but this is just space stretching we're talking about, its a dimension therefore how can the matter within be stretched and broken when its the space itself stretching and matter is merely within it, its like time dilation, its perceived as normal within although in this case as we perceive all 3D space instead of just linear like time, we may well see stretching but the dangerous effects shouldn't happen, past the event horizon you might start entering time space, the inversion of space time, where time can be moved around just like we can in space, space may or may not be linear there.