Who pays for contractors' health care?

Juan Cole pointed out this AP report, from the Times of India. The ambiguous report says a blast "injured four US contract workers". In this case, the report doesn't sound as though the four contract workers were just scraped up, but I imagine they could have easily been severely injured since others actually died in the incident.

So, who takes care of injured contractors? Am I, as a U.S. taxpayer, footing the bill for mercenaries and other military contractors in Iraq? And what about non-U.S. citizen contractors who are working with U.S. companies? Do they get medivac'ed to the nearest non-U.S. military hospital, or am I paying for their care in the green zone? If I'm not paying for their care, how not? Is the U.S. military actively billing CACI and other torturers for medical care their staff receives?