Who knows how long this poor girl could have been trapped if this cabbie hadn't been driving by at just the right time!

A girl in northern China was walking down the street recently when the sidewalk suddenly CAVED IN, and she fell about 15 feet.

A cab driver saw it happen, stopped the car right away and rushed over to help. He even climbed down to help her.  Apparently she was unconscious when he got there.  The fire department ended up having to use a ladder to get them both out, and a security camera caught it all on video.

What's truly amazing is she didn't have any broken bones!!

Authorities say water had eroded the ground under the sidewalk and created a huge pit.