The incident happened just after noon in front of Acme Windows on Somerset Street in Plainfield.
Authorities say the 67-year-old woman appeared to be texting when she fell through the open bilco doors.
She fell 6 feet to the floor below.
A girl and woman walking in the other direction saw it all, and in just a few moments, a whole crowd gathered to see what happened.
The Plainfield Fire Division extricated the woman from the hole and rushed her to the hospital for treatment of serious injuries.
The access doors were open due to the repair of gas lines in the area. You can see the helmet of a worker inside the hole at the time of the fall.
The victim is listed in serious condition.
NOTE: Raw video credit: Acme Windows via Storyful