The doctor also was a commissioned reserve deputy who worked with the sheriff's office on SWAT teams and emergencies such as meth lab discoveries, said Pierce County sheriff's spokesman Ed Troyer.
The fire was reported at 11:10 p.m. Wednesday and burned through the night, said Gig Harbor fire department spokesman Eric Waters.
The doctor's wife escaped with their 12-year-old daughter. A neighbor rescued their 8-year-old son, Waters said. Those family members and the neighbor were taken to a hospital and treated for smoke inhalation.
The boy and the girl presumed dead were twins, Waters said.
The nearly 7,000-square foot home was in flames when firefighters arrived and gutted by the fire. Heavy equipment had to be brought in Thursday to stabilize tilting walls before firefighters could look for bodies and investigate the cause, he said.
"We always wish for a miracle, but I don't think that will happen," Troyer said.
Firefighters kept the flames from spreading to neighboring homes, even as water from their hoses froze in frigid temperatures, Waters said.
"Everything we put water on has all turned to ice," he said. "It something we're dealing with."