A van that had been stripped of its rear passenger seats and packed with 17 people--most of them apparently undocumented farm workers--crashed into a tractor-trailer rig on an icy interstate early today, killing 13 people.

U.S. Border Patrol spokesman Doug Mosier said authorities found documents in the van that suggest the occupants were Mexican nationals from Chiapas and Oaxaca.

Border Patrol agent Garth Rogers said he spoke to one of the survivors and was told the van was headed to Kentucky at the time. The driver, allegedly an alien smuggler, had a list of names and amounts he was being paid for transporting the agricultural workers, Rogers said.

The van's driver apparently did not notice that traffic had slowed for an accident ahead and plowed under the back end of the tractor-trailer, Santa Fe County Undersheriff Benjie Montano said.

He said there did not appear to be any signs of braking by the van.

"It was gruesome," said towing company owner Michael Tavenner.

There was about an inch of ice on the road where the crash occurred, Tavenner said. An overnight storm had left 2 to 3 inches of snow in the region and wind had blown snow into drifts 16 inches deep.

The crash occurred about 2 a.m. on a straight stretch of Interstate 40 about 35 miles east of Albuquerque.

Three surviving passengers, two men and a woman, were in satisfactory condition at University Hospital and another man was listed in critical condition, hospital spokeswoman Cindy Foster said. All 13 killed were men.

The tractor-trailer's driver did not require hospitalization.