BuzzFeed Editor-in-Chief Ben Smith says he learned from a family member that the 33-year-old died early Tuesday.
Hastings wrote about politics for the popular news site and has written books dealing with the wars in Afghanistan and Iraq.
He won a Polk Award for magazine reporting for his Rolling Stone cover story "The Runaway General."
The story was credited with ending Gen. Stanley McChrystal's career after it revealed the military's candid criticisms of the Obama administration.
There was a car crash early Tuesday in the Hancock Park neighbourhood of Los Angeles that killed a man, but coroner's officials could not confirm whether Hastings was the victim.