The award-winning journalist and war correspondent Michael Hastings – who wrote a Rolling Stone story that brought down a top US general – has died in a car accident in Los Angeles.

Hastings won a Polk award for magazine reporting for his Rolling Stone cover report The Runaway General. The story was credited with ending General Stanley McChrystal's career after it revealed the military leader's candid criticisms of the Obama administration. Hastings also wrote for BuzzFeed.

Rolling Stone ran a report late on Tuesday confirming Hastings had died in a car crash that morning and praising him as a "fearless journalist".

General Stanley McChrystal. Photograph: Manuel Balce Ceneta/AP

McChrystal was the top US general in Afghanistan when Hastings documented the general making remarks like: "Are you asking about Vice-President Biden? Who's that?" and, along with his aides, criticising the Obama administration's handling of the war and their civilian commanders in the White House.

Barack Obama, announcing McChrystal's removal in light of the story, said: "The conduct represented in the recently published article does not meet the standard that should be met by – set by a commanding general. It undermines the civilian control of the military that is at the core of our democratic system."

Rolling Stone said that in all his work Hastings had refused to "cosy up to power".

"While other embedded reporters were charmed by McChrystal's bad-boy bravado and might have excused his insubordination as a joke, Hastings was determined to expose the recklessness of a man leading what Hastings believed to be a reckless war."

Matt Farwell, who worked with Hastings on some of his recent pieces, told Rolling Stone: "As a journalist he specialised in speaking truth to power and laying it all out there. He was irascible in his reporting and sometimes/often/always infuriating in his writing: he lit a bright lamp for those who wanted to follow his example … He always sought out the hard stories, pushed for the truth, let it all hang out on the page."

Hastings is survived by his wife, the writer Elise Jordan.