Rashah McChesney, Associated Press
A firetruck provides water for a crew on the ground as firefighters backburned near Funny River Road Wednesday May 21, 2014 in Soldotna, Alaska. Fire crews have been battling a wildfire that has grown to more than 44,000 acres in three days.

An Alaskan wildfire that has burned 151 square miles in the Kenai Peninsula is threatening about 150 cabins, vacation homes and year-round residents in three communities threatened by the rapidly growing blaze, fire officials said Saturday.

They could not estimate how many people have been told to be ready to leave their residences because many of them are vacation homes. One of the communities threatened is a popular area for retirees.

Fire spokeswoman Michelle Weston said about 50 homes were evacuated briefly late Friday night when the fire kicked up. People were allowed to return to their homes when fire activity calmed down, but were warned they could be evacuated again.

The Funny Ridge Fire burning in the 1.9-million-acre Kenai National Wildlife Refuge was 20 percent contained as of Saturday morning, Weston said. The fire grew by nearly 29 square miles between 5 p.m. and 11 p.m. Friday.

About 409 firefighters are assigned to the fire, which was one of several large wildfires burning in Alaska. They are getting help from an Oregon fire crew and some water scoopers have been flown in from Alberta, Canada.

The fire is burning in three directions with most of the containment lines on the north and west sides, Weston said.

The Funny Ridge Fire was the only wildfire rapidly spreading Saturday in Alaska, which is experiencing unusually dry conditions because of unseasonably warm spring temperatures. High wind is also a challenge for people fighting the Funny Ridge Fire.

"We don't normally have a large fire like this so early in the season," said Weston, who is part of the Alaska Interagency Management Team, which includes the state Division of Forestry and federal and local officials.

Alaska is so dry that the state Division of Forestry issued a statewide outdoor burn ban on Friday afternoon, Weston said.

Wildfires in Alaska's remote areas are not unusual during the summer months, with an average of a million acres burned each fire season, she said. But the Funny Ridge Fire is unusual because it is burning so close to recreation areas known for fishing and hunting.

Alaska's outdoor recreation season begins in May.