The blaze was reported around 10:40 a.m. at a single-story home in the 800 block of East Angela Street.
Fire Department spokeswoman Sabina Imrie said the victim, identified as Deonna Zuffa, who is about 40 years old, walked into the home, heard an explosion and the house was then consumed by fire.
Twenty-two firefighters worked to bring the blaze under control and its cause remains under investigation.
The fire caused some damage to two neighboring houses, burning the attic of one and causing some exterior damage to a wall of another.
Zuffa's husband and two children, who both attend Pleasanton Unified School District schools, were not in the home when the fire broke out and there was no other report of injuries, Imrie said.
Zuffa was taken to Eden Medical Center in Castro Valley and then transported to St. Francis Memorial Hospital in San Francisco for treatment.
Imrie said the fire caused more than $1 million in damage to the home and its contents, which included a number of muscle cars in the garage.
Imrie said staff at Pleasanton Middle School is starting a fundraising drive in response to the fire. To make a donation, call Karen Buchanan at (925) 426-4390.