Learning about article

The following paragraph is taken from the yanoo.com news online:


"A former student dressed in black opened fire with a shotgun and two handguns from the stage of a lecture hall at Northern Illinois University on Thursday, killing five students and injuring 16 others before committing suicide, authorities said."


I tend to use "the" to begin the paragraph, so it will be written like this: "The former student dressed in black...." not started with "A...".

Why? Because, in the above sentence, the writer of the news has stated "....dressed in black", to make the "former student" become a specific object.

Could you guys explain to me why he/she started the paragraph with "A", and not with "The"?

Thank you very much.

Hello,

After reading an article again about the use of "the", I think I know why the writer of the news use "A...." instead of "The...." when he/she started the paragraph. Because, he [the person who brings the gun] is not the only person over there who dressed in black. There're so many other person who dressed in black.

Am I correct?

It's got nothing to do with him being dressed in black. It's because he hasn't already been referred to, therefore you would need to use the indefinite article at the beginning of the article. When referring to him subsequently you would use 'the'. If you just launched in using 'the student' people reading would be wondering which student you were referring to.

Hello Guest,

Thank you for your explanation.

I though it was about the man who dressed in black.