He wouldn't confirm reports that his government is probing several deaths, but said some "real concerns" have been raised about the agency's operational matters and its use of taxpayer dollars.
"We'll wait and get the facts before us and make the appropriate decisions," he said Thursday.
Health Minister Deb Matthews was also tightlipped about how many deaths her ministry is currently probing, but said it's required to look into every incident that comes to its attention about air and land ambulances. Between 2007 and 2011, the ministry says it conducted an average of 27 investigations involving air ambulance services per year.
ORNGE said late Thursday afternoon that the ministry's Emergency Health Services Branch is investigating 13 incidents related to air ambulance transports.
The ministry also told the agency that in three of these cases, the regional coroner will be provided with a copy of the report, ORNGE said. But it can't provide any other details.
"The Ontario Coroner has not contacted ORNGE directly for information with respect to any transports," chief operating officer Tom Lepine said in a statement.
"We have been advised that the coroner is not conducting any specific investigation into ORNGE or transports involving ORNGE."
Matthews cleaned house at the agency last week after months of controversy surrounding its questionable business practices, posh headquarters and high executive salaries.
She replaced CEO Chris Mazza — who was paid $1.4 million a year — and the entire board of directors.
The government hasn't said how much severance it will have to pay Mazza, who went on indefinite medical leave days after his salary was made public.
ORNGE, which performs about 20,000 transports a year, will also have to wind up its for-profit side businesses such as ORNGE Peel, ORNGE Global Air and ORNGE Global Real Estate and operate as a non-profit entity.
The sweeping changes came after the auditor general and the Ministry of Finance both sent audit teams into ORNGE, which receives about $140 million a year from the province to operate a non-profit air medical rescue and transport service.
It's "unfortunate" that these revelations are emerging in the media, instead of the government that was supposed to be keeping an eye on ORNGE, said NDP critic Jonah Schein.
"I think it's time for this government to come clean," he said. "This is scandalous and we need to get to the bottom of this. This is a mess and it needs to be cleaned up."
The Progressive Conservatives say the government ignored their complaints about ORNGE for months, acting the same way it did when a scandal broke at eHealth Ontario over untendered contracts and expense account abuses.
The Tories say they warned Matthews back in April that the agency wasn't living up to its obligations and that public health dollars were subsidizing empire-building that was going on under the cover of a public air ambulance service.
McGuinty said Thursday he couldn't recall when he became aware of the problems at ORNGE, even though top government officials — including key members of his staff — were briefed a year ago on many of its controversial money-making and spending plans.
ORNGE did make a proposal to the government about a "private operation," but gave assurances that no public dollars would be used, he said.
"Concerns have been raised along the way, and that's why we're taking the steps that we are now," McGuinty added.