I was finishing my novella when I heard about the terrorist attacks in Paris (I pray for the souls of the victims). I was surprised to know that circumstances revolving around the violent attacks were somehow similar to those in my novella. In my story, there were also eight attackers who each had a specific target and killed almost one hundred fifty civilians. The only thing that made my story different was that my terrorists were communist rebels, not Muslims. Should I change the plot line?
Your story is fiction, don't sweat it. As far as bad taste, I write for a living. Life happens. I don't consider it bad taste. If anything, it is showing concern for the actual events in question and being thoughtful about implications. The typical time frame from manuscript to publication is a year, unless you're REALLY lucky or already established, in which case you can cut in half. May God help all those tragically affected, but don't let it stop you from doing your job. It beats the crap out of working for Target.
I've heard of a few cases of TV shows and movie releases being delayed because the fictional events paralleled unpleasant real life events too closely, and so they felt it would be in bad taste. But they don't throw the story away, they just sit on it for a little while. Because human nature is that when something terrible happens, we are all horrified for a few days or weeks, but then we tend to forget about it and get on with our lives. If you wrote, say, a novel about a country launching a sneak attack on another country that closely paralleled Pearl Harbor today, few would find this offensive or in poor taste.
Writers are often praised for being insightful and prophetic when events in their book happen in real life. Of course that doesn't work if the book isn't published until after the event, even if written before.
I'm suddenly reminded of a lecture I heard years ago by a writer who had written a magazine article back in the 1950s explaining why he thought Mount Everest would never be climbed. In between when he wrote the article and when it was scheduled to be published, Sir Edmund Hillary succeeded in climbing Mount Everest. As the author described it, "This presented the magazine with a difficult ethical dilemma: Should they cancel the article and forfeit the $10 they had paid me for it, or should they go ahead and print it and make me look like a complete idiot. It took them about a second and a quarter to decide. And so I became the only person in history to predict that Mount Everest would never be climbed, six months after ..."
Use the opportunity to write a preface or afterward that describes how you heard about the true event and the impact it had on you. This has the added benefit that you're implicitly denying that you had taken advantage of the event for your story. If you decide to change the story in any way based on the event, you could use an afterword to (briefly) describe what you changed and why.
While not exactly the same this sort of thing happens in creative fields.
Tom Clancy's novel Debt of Honor had a terrorist deliberately flying an airplane into the capital.
The film SpaceCamp, in which an accident on the launch pad endangers children by sending them to space was to be released after the launch of Challenger in 1986 - the film was of course delayed after the Challenger explosion.
Sometimes reality is stranger than fiction.