subhajit123 posted:It is not that accidents like this hadn't occurred/haven't occurred before but the number of deaths had never risen/have never risen to that point before.
I strongly disagree with Yama here. You need the present perfect in that sentence, in both of the cases: "It is not that accidents like this haven't occurred before, but the number of deaths has never risen so high."
This is news, Subhajit, so the relevance to the present is undeniable. The fact that the accident has been located in "yesterday" in the text preceding the sentence doesn't affect your ability to use the present perfect in the sentence.
I made three changes to the second independent clause. I added a comma before the beginning of the second independent clause, I changed "have" to "has" ("number" is singular), and I changed "to that point before" to "so high."
Years from now, you might wish to refer back to this accident. If you were to construct a similar sentence, you might begin with "It was not that . . .," and then the past perfect would be in order:
- It was not that accidents like this hadn't occurred before but the number of deaths had never risen so high.