A house fire tangled up traffic on South 27th Street as students made their way back to school Wednesday morning.

A sofa leg sitting on a space heater’s power cord was to blame for the fire at 2324 S. 27th St., according to Fire Investigator Damon Robbins.

He said one of two tenants woke to the sound of glass breaking. She woke her roommate, they investigated and found the fire in the living room.

Robbins said the fire still was small, and the smoke detector hadn’t sounded yet. Jessica Lee and Jill Hain got out safely and called 911 just before 7 a.m.

Firefighters asked police to block off 27th Street from Sheridan to Van Dorn for about an hour as they worked to put out the fire and clean up. They’d reopened southbound lanes by 8:30 a.m., but traffic was congested as commuters headed for work and parents drove their kids to nearby schools for the first day back after Christmas vacation.

It was hard to tell how long the cord may have smoldered before the fire started, Robbins said. One of the tenants plugged in the space heater after 3 a.m. to keep two pet turtles warm. The turtles survived.

The fire was contained to the room in which it started, but heavy smoke spread through the house, Robbins said. He estimated $50,000 damage to the home, owned by Jerry and Maxine Hain, and $20,000 damage to possessions inside.

The tenants did not have renters insurance.

Robbins reminded people to be careful with space heaters and to be sure not to cover power or extension cords with rugs or anything else that could start on fire.

He advised against using space heaters while sleeping, against using extension cords with space heaters and against leaving heaters plugged in when they’re not in use.

This time of year, Robbins said, people need to be especially careful with space heaters and with candles and fireplaces.