An elderly woman was reportedly sexually assaulted at a care home, police have said.
Greater Manchester Police (GMP) said they were called out to reports of an unknown man on the premises in Oldham, during the early hours.
An elderly woman was then taken to hospital after further reports of a serious sexual assault and assault, police said.
A 21-year-old man was arrested on suspicion of serious sexual assault.
He has been taken into custody for questioning.
All other care home residents are safe and visits have been temporarily restricted, police said.
Supt Phillip Hutchinson, from GMP, added: "We understand the effect this will have on residents, families, and staff at the care home and the wider community.
"Alongside our criminal investigation, we are working with Oldham Council and partner agencies to ensure the safeguarding and security of residents."
He asked anyone with information to contact police.
An elderly woman was then taken to hospital after further reports of a serious sexual assault and assault, police said.
A 21-year-old man was arrested on suspicion of serious sexual assault.
He has been taken into custody for questioning.
All other care home residents are safe and visits have been temporarily restricted, police said.
Supt Phillip Hutchinson, from GMP, added: "We understand the effect this will have on residents, families, and staff at the care home and the wider community.
"Alongside our criminal investigation, we are working with Oldham Council and partner agencies to ensure the safeguarding and security of residents."
He asked anyone with information to contact police.