Four people died in a duplex home fire early Saturday, and a fifth was in critical condition in Hennepin County Medical Center.

The county medical examiner's office said the dead included a woman in her 40s and her two sons, ages 12 and 22, whose names were withheld, and a man identified as James Jackson, 21, who was visiting the home. The person in critical condition was believed to be Jackson's brother.Arson investigators were trying to determine the cause of the fire.