I've seen in the following page I should use the present perfect in a sentence with an unfinished time word. http://www.perfect-english-grammar.com/present-perfect-or-past-simple.html
However in the news I often see the past simple instead, example:
A woman died today
A man was killed today.
Why is the past simple correct ? Could it be possible to say these instead?
A woman has died today
A man has been killed today.