ALONG THE GUNFLINT TRAIL -- Whipped by hot, dry wind that created conditions authorities called explosive, the Ham Lake wildfire charged into new territory Thursday, prompting more emergency evacuations, destroying more structures and expanding at least 5 miles into Canada.

As trees exploded into giant balls of flame on the ridges above the north shore of Gunflint Lake, authorities ordered people to leave their homes, cabins and resorts from Cook County Road 92 westward along the 60-mile dead-end trail, including residents on Gunflint, Loon and Sutton lakes.

Fire officials later expanded that mandatory evacuation an additional 10 miles to the Poplar Lake fire hall, in the area of the Trail Center restaurant and store.

Authorities said the evacuation was expanded because a wind shift to the north late Thursday afternoon caused the fire to jump Gunflint Lake. Superior National Forest supervisor Jim Sanders told a crowd in Grand Marais that the extent of the fire on the lake's south side was unclear, but that authorities plan to fly over the lake overnight and use an infrared camera to get a better idea how far south the fire had spread.

Late Thursday night, the Minnesota Interagency Fire Center reported that additional structures had been destroyed. No specifics were offered, but the fire already had destroyed 45 structures.

"Today we got our butt kicked," Sanders said. "We've got a tiger by the tail. When the weather changes we, can get our arms around it."

The fire grew from almost 35 square miles Wednesday to almost 47 square miles Thursday, said fire official Bill Heston.

Almost 500 people are fighting the fire, Heston said, and the cost so far is $1.9 million.

No injuries to either the public or firefighters have been reported, a fact Sanders called "phenomenal."

Since the fire ignited Saturday near Ham Lake from what authorities suspect was a campfire, about 45 structures have been destroyed. At least as many structures in the fire's path were saved, due, in large part, to outdoor sprinkler systems, installed after a 1999 windstorm downed millions of trees in and adjacent to the Boundary Waters Canoe Area Wilderness.

Businesses evacuated Thursday include the landmark Gunflint Lodge, which firefighters had used as a staging area, Gunflint Pines Resort and Heston's Lodge, all of which had been preparing for an influx of weekend guests for the fishing opener.

Necessities and heirlooms

At Gunflint Pines, which was enveloped in a gray-yellow cloud of smoke, owner Shari Baker and helpers filled their vehicles with family belongings, including pictures and her husband Bob's rifles and compound bow. He couldn't help. He was out fighting the fire with the Gunflint Volunteer Fire Department.

She carted her computer, cash register and records to a waiting Suburban; she and employees planned to call this weekend's customers from a motel in Grand Marais, and warn them that the lodge might be closed.

Nearby, Matt Claybaugh, who had traveled from Hawaii with his three boys and a buddy to spend the opener at a log cabin that had been in his family for generations, filled a mini-van with family heirlooms. In his haste, he forgot to load an antique Seagull outboard motor that had been his grandfather's.

"I feel bad about that -- the first thing my dad asked me when I called him was, 'Did you take the Seagull?' " Claybaugh, 42, said after settling into a motel in Grand Marais, which, 50 miles from the fire, was shrouded in smoke.

Several lodges had sprinklers on their roofs and had been spraying the areas surrounding their buildings for at least two days to try to minimize the chance of fire consuming them.

Fire officials said the fire expanded significantly into Canada, pushed east as many as 5 miles by 35-mile-per-hour winds.