The cost of fighting the Station fire stood at $88 million Friday as firefighters continued to make progress in containing the 3-week-old blaze.

With full containment expected Tuesday, the fire could end up costing more than $100 million to fight.

"We keep evaluating the costs every day," said Tom DeBellis of the U.S. Forest Service.

The Station fire, which has destroyed more than 80 dwellings and killed two firefighters, was 81% contained as of Friday. About 1,500 homes remained threatened in the foothills above Sierra Madre, Arcadia and Monrovia as the blaze continued burning along its eastern flank.

DeBellis said firefighters continued to complete back burns, with the hope of surrounding Mt. Wilson and vicinity in a "black line" fire buffer.

Meanwhile, detectives hunting for the arsonist responsible for the fire have received tips from about 50 people and will pursue every one of them, officials said.

Lt. Liam Gallagher of the Los Angeles County Sheriff's Department's homicide unit said investigators treat every tip seriously because sometimes the smallest piece of information can lead to other clues that solve a case.