Woman dies in Adelaide house fire

A 71-year-old woman has died in a house fire in Adelaide's north.

Firefighters were called to a fire at a unit in Semaphore Park at about 3pm on Tuesday.

The woman's companion and an off-duty police officer tried to enter the house but were forced back by the blaze, which took about 25 minutes to extinguish.

Police are investigating and will prepare a report for the coroner.