This is something that crops up on the BBC a lot and irks me. For example, from a story today:
One woman is critically ill and three others have been injured after they were stabbed near a supermarket car park in west London.
To me, you are ill (or sick) if you have, for example, contracted a disease and using it in the sense of someone being injured is wrong.
Google gives the definition of ill as "suffering from an illness or disease or feeling unwell." and I'm sure that a car crash or stabbing would certainly make you feel unwell, but I still don't think it's right. Is it?