6 p.m. " Interstate fire burning off I-80 near Tahoe Donner at 170 acres

Fire officials say the Interchange Fire is at about 170 acres.

The fire is burning off westbound Interstate 80 near the Donner Lake interchange and up to about a quarter mile from the Tahoe Donner Subdivision.

Westbound I-80 was closed from about 2-5 p.m. One westbound lane reopened at 5 p.m.

No evacuations have been ordered, but Truckee Fire Protection District Chief Bryce Keller said a potential evacuation site would be at the Alder Creek Middle School.

Four helicopters and six airtankers along with 35-50 pieces of equipment and 250 firefighters are on scene, according to Calfire's JoAnn Cartoscelli. Efforts are focused on keeping the blaze from moving up into Tahoe Donner, a 6,000 home subdivision.

At approximately 4:30 p.m. Cartoscelli reported that the fire was holding in an area previously burned. There have been several fires in the Negro Canyon area over the last five decades, including the Donner Fire in 2003 and the Donner Ridge Fire of 1960, which burned from the Donner Lake interchange through what is now Tahoe Donner.

Downed power lines forced the closure of westbound Interstate 80, but one westbound lane has been opened as of 5 p.m. Reports are that a tree trimming crew dropped a limb into a power line, sparking the fire.

The fire moved up a drainage to the edge of the subdivision. Fire trucks were positioned throughout Tahoe Donner in case structure protection is needed.

Winds are blowing at about 20 mph.

Truckee police officers are limiting traffic into Tahoe Donner to local traffic only.

Come updates to come.