A man has been arrested on suspicion of attempted murder after a house was set on fire.
The 34-year-old was detained by Greater Manchester Police (GMP) officers on Saturday morning at an address in Leigh.
He is in custody for questioning.
A house on Montreal Street in the town was attacked in the early hours of Tuesday morning when windows were smashed before a flammable liquid was thrown into the property and set alight.
The couple who were in the house managed to escape the flames but the woman, who is in her 60s, was taken to hospital where she remains in a critical condition.
It is believed she has suffered life-changing injuries as a result of the attack.
Detectives are still urging people to come forward with information, no matter how small.
Detective Chief Inspector Stuart Wilkinson from GMP’s major investigations team said: “Following a warrant this morning we now have one man in custody. However, this does not mean our investigation stops here.
“We are doing lots of work behind the scenes to find those responsible for this horrendous attack which has left a woman with life-changing injuries.
“We are still eager to speak to anyone who might know something about this incident and I’d appeal to you to get in touch.”
Anyone with information is asked to contact police on 0161 856 9908 or call the independent charity Crimestoppers, anonymously, on 0800 555 111.