Shortly after 12.40am on Tuesday 16 October 2018 police were called to reports that a house was on fire on Montreal Street.
The occupants escaped from the address and a woman, believed to be in her 60s, was taken to hospital with serious burn injuries. She remains in a stable condition.
Police would like to trace two men who were seen outside the property around the time of the incident.
A scene is in place at the property and a joint investigation is underway alongside Greater Manchester Fire and Rescue Service.
Detective Inspector Graham Clare from GMP’s Wigan Division said: “This was a horrendous attack in which a woman has been left with serious injuries, and my thoughts are with her and her family.
“Our investigation is ongoing in order to establish the full circumstances of what happened and find whoever is responsible.
"I would urge anyone who witnessed people acting suspiciously in the area in the early hours of Tuesday morning to come forward and talk to police.
“There will be an increased police presence in the area while our investigation continues, and I would encourage anyone with questions or concerns to approach the officers at the scene.”
Anyone with any information is asked to contact police on 0161 856 7182, alternatively call 101 or Crimestoppers anonymously on 0800 555 111.