JACKSONVILLE, Fla. – Heather Frez knew she had to do something after she picked up the phone early Monday morning to hear that her neighbor’s home was on fire.

Frez, 57, said she dialed 911 and rushed over to the house on Van Sickle Road to find it going up in flames. But she couldn’t stand by and wait for help to arrive.

“I took a brick and broke that [front] window and yelled for her name,” she said. “I bashed on the door, couldn’t get it, it was really locked tight. So I went around the back and broke the window.”

But after shattering the glass, Frez could not make it past the suffocating smoke that was filling the home. She had done everything she could.

“Couldn’t see anything inside," said Frez. "It was bad."

By the time firefighters answering Frez’s call arrived about 7 a.m., her neighbor was dead. After breaching the door with a sledgehammer, they found the woman near the back of the home.

Rescuers could not resuscitate the woman. But they did, however, manage to rescue the woman’s dog from the flames.

Tom Francis, spokesman for the Jacksonville Fire and Rescue Department, said the State Fire Marshal’s Office is investigating the fire, which appears to have been sparked accidentally.

The middle-aged victim, whose name has not been released, leaves behind a daughter and son, Frez told News4Jax.