The condition of a Westbrook woman injured in a fire in her apartment building on Friday has been upgraded from critical to serious, according to Massachusetts General Hospital in Boston.

Madelena DuDu Kassa, 51, suffered life-threatening burns in the fire that started around 10 p.m. on a stove in her first-floor apartment at 94 Pierce St. She was taken by ambulance to Maine Medical Center in Portland, then flown by LifeFlight helicopter to Massachusetts General.

She remained in critical condition Saturday night, but her health had improved by Monday.

Kassa’s husband and two grown sons who also live in the apartment were not injured. Three members of a family of six who live upstairs were treated for smoke inhalation and released.

The building, owned by Memana Abraham of South Portland, was destroyed by the fire. The American Red Cross is helping the displaced residents.