On April 24, while constructing the Kaiser Permanente medical offices in San Diego, construction workers heard the meows of kittens and discovered them inside a huge 60-foot steel column which had been transported almost 500 miles by truck from the San Francisco Bay Area.

After hearing the cries of the kittens they tilted the column and the magnificent five slid out. They been appropriately named: Jack, Chisel, Crowbar, Piper and Rebar.
They are currently being cared for at the San Diego Humane Society who plan to keep them in foster care until they are eight-weeks-of-age when they will be put up for adoption. There are currently four-weeks-of-age.
How they got into the steel column and when they got into it is unknown. I wonder if their mother (and this is the most likely explanation) created a den inside the column which must have seemed ideal at the time if it had been static for a while. It was taken away on the back of a truck while the mother was absent perhaps looking for food. If that is correct then the mother will be distressed having lost her kittens. Likewise the kittens must have been very anxious and it’s amazing that they survived.
Source: people.com

That would have been great if they had done that. I would have been doable as they know exactly were the steel came from.
Oh yeah that is extremely sad for the mother, losing her five newborn babies like that. Nothing could be worse. I’d try to back track and find her, and reunite them. I don’t care what the cost would be.