New Jersey officials said on Monday they were investigating why a utility company shut off power last week at the Newark home of a woman in hospice care who then died after her electric-powered oxygen tank stopped operating.

Family members of the woman, Linda Daniels, said she gasped for air for hours on Thursday until she died of congestive heart failure. The company, Public Service Electric and Gas Company, had cut off power to her home that morning because of overdue bills.

The family said they pleaded with the company to restore electricity, telling customer service representatives that Ms. Daniels, 68, depended on oxygen equipment in order to breathe. Power was eventually returned to the home on Friday.

“She was scared, and she was holding our hands tightly,” said Desiree Washington, Ms. Daniels’s daughter. “She was horrified. We were all horrified.”