The blaze was reported around 5:30 p.m. on Taylor Road. Twenty-mile-per-hour winds pushed the fire from one house to another, Battalion Chief Dave George said.
No fire hydrants are on the island, which created another challenge for the nearly 60 firefighters who responded, according to George.
The firefighters shuttled in more than 30,000 gallons of water to the island and were able to save the third house "by literally pushing the fire right back out against the wind," George said.
The flames were controlled by 7 p.m., George said.
An elderly woman suffered from smoke inhalation, and two firefighters endured heat-related difficulties, according to George.
The blaze caused a total of $1.5 million in damage to the houses.
Three families have been displaced but George did not know if the American Red Cross was providing assistance.
The cause of the fire remains under investigation.