"Two people got hurt and five people died in the tragedy"

Solution 1:

It depends on the context. In early news reporting, where the aims these days seem to be speed and sensationalism rather than factual accuracy, the focus is likely to be on the number of deaths. Thus you’ll see a headline like:

Five killed in tragedy

Maybe expanded in an article as:

Five people died and two others were injured in the tragedy

But in a formal investigation report of the incident you’re more likely to read:

Injuries: 7 (5 fatal, 2 serious)

Solution 2:

"Injuries" and "deaths" are disjoint groups usually, though you may sometimes speak of a "fatal injury" (an injury that later leads to death).

They may both be classified as casualties of an incident.

Solution 3:

Usually, deaths are deaths and injuries are injuries, so the dead are not counted as injured.

And I'd say "injured" instead of "got hurt". "Got hurt" makes me think of kids, of children. "Mommy, I got hurt!" sort of thing. Not to mention that "got hurt" can mean something else, as in "That remark really hurt my feelings!".

The victim of a stabbing (btw, "someone stabbed someone else with a knife", "to stab a knife into someone", while (I think) grammatically correct, just sounds weird) would count as injured. Until he dies (if he does so). Then he counts as dead.