NORIAS, TX — For many Mexican immigrants seeking a better life in Texas and beyond, the path is familiar. So are its myths.

The route traverses the world's largest privately held ranch, the 825,000-acre King Ranch south of Corpus Christi, where 50,000 cattle graze among cotton, grain, scrub brush and oil derricks. The dangers are well documented — nine illegal immigrants died in searing heat this summer.

There is a misbelief that if you sleep between the tracks, snakes won't get you.

Copperheads, corals, rattlers and other venomous snakes also infest the range, and authorities say that may explain why six men were sleeping in the path of a Union Pacific freight train that crushed them to death early Monday.

Unfortunately, trains will.

"There is a great (misbelief) that if you sleep between the railroad tracks, snakes won't get you," Union Pacific spokesman Mark Davis said. "Unfortunately, trains will."

The six unidentified men, believed to be undocumented immigrants from Mexico, were killed around 3:15 a.m. by a 105-car train carrying mixed freight on its way to Brownsville from Houston.

Train engineers said they never had a chance to avoid the men.

"The train crew saw some debris on the tracks," said Letty Garza of the U.S. Border Patrol. "That next split second, they saw heads raise up and then six people were killed instantly."

An agent happened to be working near the accident.

"He heard the train, then all of a sudden he heard something — he described it as a loud slapping," she said.

The train was traveling about 45 mph and took a half-mile and several minutes to stop, Garza said. No cars derailed.

Even after authorities cleaned up the site, pieces of bloody human tissue remained between the tracks, with crushed cans of beans, packages of tortillas and a roll of toilet paper — provisions for the journey — strewn about.

Investigators will try to identify the men through fingerprints and dental records, said Kenedy County Sheriff Rafael Cuellar Jr. One man was carrying an identification card.

The sheriff said similar train accidents have happened in his county, but none involving so many men. Union Pacific is working with the Border Patrol to discourage immigrants and transients from seeking refuge on the tracks.