Two separate sources are reporting that Supreme Court Justice Antonin Scalia was found dead of natural causes today at a West Texas ranch. The first comes from a San Antonia paper:

"I was told it was this morning," Biery said of Scalia's death. "It happened on a ranch out near Marfa. As far as the details, I think it's pretty vague right now as to how," he said. "My reaction is it's really unfortunate with any death. And now, politically, in the presidential cycle we're in my educated guess is nothing will happen before the next president is elected." 

The U.S. Marshal Service, the Presidio County sheriff and the FBI were involved in the investigation.
Officials with the law enforcement agencies declined to comment.

A federal official who asked not to be named said there was no evidence of foul play and it appeared that Scalia died of natural causes.

The second comes from an El Paso television station:

EL PASO -- An El Paso source close to Justice Antonin Scalia tells ABC-7 that the 79-year-old died in his sleep last night after a day of quail hunting at Cibolo Creek Ranch outside of Marfa, Texas.

The Justice did not report feeling ill and retired to his room after dinner. The source, who was traveling with Scalia, told ABC-7 an El Paso priest has been called to Marfa.

We'll update this post with more as it becomes available.