A surprised worker at a Cox Communications warehouse opened the box and found the black kittens. They were taken to the San Diego Humane Society with their umbilical cords still attached.
It's believed that their mother gave birth and left them in the box temporarily, thinking it was a safe spot.
Humane Society nurse Jenny Bonomini says the kittens, named Mouse and Wifi, are happy and putting on weight. Lucky for them, they are in one of the few full-time kitten nurseries in the country.
The Associated Press contributed to this report.