It is understood an elderly man, who is a resident at Lisnisky Care Home in Portadown, is being treated in hospital after sustaining a number of injuries.
Two members of staff were arrested on suspicion of grievous bodily harm with intent.
The alleged incident happened on 14 April.
They were released on police bail after being interviewed, and police say their investigation is at an early stage.
An increased level of monitoring and management oversight had been put in place at Lisnisky Care Home said a spokesperson for its owner, the Four Seasons Health Care Group.
It was taking appropriate measures "to ensure the safety and wellbeing of residents, which is always our first consideration", said the group in a statement.
But it added that it would be wrong to comment or speculate about the ongoing investigation.
Upper Bann UUP MLA Doug Beattie said the elderly deserved to be treated with respect and cared for in a dignified manner, and that vulnerable residents must be protected.
"There is a matter of trust between those who avail of the private care home system and those who deliver that care," he said.
"There can be no place in our care system for the abuse of the most vulnerable."
Lisnisky Care Home provides both nursing and residential care to elderly people who are frail and mentally ill.
Several members of staff have been suspended following allegations of abuse at a County Armagh care home, the BBC understands.