Daisy,
This has been all over the local news here.
While the garage was under construction, and no cars parked at that garage, they are worried about other structures close by, being damaged. I heard last evening there are a number of cars in a nearby garage that where not allowed to retreive them.
I suspect, the investagation will find that someone wasn't using the correct materials for constructing something of this nature. Either a cheaper mix of concrete, or not enough re-bar.