Andrew Breitbart dies at 43

Controversial Internet activist Andrew Breitbart died Wednesday night. He was 43.

Conservative media entrepreneur and activist Andrew Breitbart died unexpectedly overnight, CBS News has confirmed with the Los Angeles coroner's office and his attorney.

Breitbart died just after midnight at Ronald Reagan UCLA Medical Center, Larry Dietz in the L.A. county coroner's office told CBS News. Breitbart's father-in-law Orson Bean told the Associated Press that Breitbart was walking near his house in the Brentwood neighborhood when he collapsed. His website said he died of natural causes.

The 43-year-old online publisher, who ran multiple sites including Breitbart.com and BigGovernment.com, was known for breaking news and creating narratives that stirred controversy for the Democrats.

Last year, Breitbart's sites published racy photos of Rep. Anthony Weiner that eventually compelled the New York Democrat to resign. Breitbart also last year published a video, taken out of context, that created a controversy surrounding then-U.S. Agriculture Department employee Shirley Sherrod.

Breitbart is survived by his wife Susannah Bean Breitbart, 41, and four children.

A message posted on Breitbart's websites on Thursday read, "We have lost a husband, a father, a son, a brother, a dear friend, a patriot and a happy warrior. Andrew lived boldly, so that we more timid souls would dare to live freely and fully, and fight for the fragile liberty he showed us how to love."

Conservatives Thursday morning mourned Breitbart's death. Upon learning the news, Republican presidential candidate Rick Santorum called it "shocking."

"What a powerful force," he said of Breitbart. "It's almost - you think of anybody out there who's just got more energy, and just, out there constantly, driving and pushing. What a huge loss, in my opinion, for our country, and certainly for the conservative movement."

Erick Erickson of the conservative blog RedState.com said Breitbart's death was "like a supernova has gone dark."

This article was originally posted on CBSNews.com.

CBSNews.com political reporter Lucy Madison and CBS News/ National Journal reporter Rebecca Kaplan contributed to this report.