"Straight outta Edmonton: Chilling video captures moment gunman dressed in Muslim robes opens fire on a teenager in broad daylight in a quiet north London cul-de-sac"
Is straight outta not a slang word? Why can it be used in an online news article?
Outta is an example of eye dialect, which means writing things in the way they're pronounced rather than strictly as they're spelled.
"Straight Outta _____" is a reference to Straight Outta Compton, the debut album by American rap group NWA, or the film of the same name about NWA.
Compton, California, the home of NWA, was known as a violent place; hence, "Straight Outta _____" makes sense as a reference because the article is about a violent act.
Yes, "outta" is a slang word. But there's no law that says that news headlines cannot use slang. News headlines are often intended to be attention-getting.
In this case, there is a popular move called "Straight Outta Compton". I haven't seen the movie but I understand it's about a group of young men from a rough, violent neighborhood. The headline is presumably an allusion to this movie.