A Manhattan high rise fire that killed an elderly woman Monday night is under investigation. The flames broke out around 7:30 p.m. inside a 15th floor apartment located at 70 La Salle Street near Broadway in Morningside Heights. Firefighters found an 88-year-old woman in the apartment and took her to the hospital where she died. An 86-year-old man was also taken to the hospital in critical condition. No word yet on what may have caused the fire.