Northern Territory Police are calling for witnesses in relation to a structure fire in Alice Springs overnight.

At around 11pm, Police and the Fire Rescue Service responded to a structure fire at a residence in the Hidden Valley Town Camp.

St John Ambulance conveyed two people to Alice Springs Hospital in a serious condition.

The circumstances around what caused the fire are under investigation.

Police are urging anyone with information to contact 131 444 or you can report anonymously through Crime Stoppers on 1800 333 000. Please quote reference 9839977.