A van loaded with farm workers and driven by an unlicensed driver slammed into a truck on a remote road in early morning darkness today, killing 13 people and renewing worries about the safety of laborers who often crowd into vehicles to get to work in the fields.

The 1983 Dodge Ram van smashed like an accordion on impact. Most of the 10 men and five women in the van were sitting without seat belts on two carpeted benches installed on each side, California Highway Patrol Officer Brian Yokley said.

It's illegal in California to have anyone ride without proper seats and seat belts, but certified farm vehicles are excluded from the law. This van received its last annual certification in 1997, but had not been certified since, the highway patrol said.

The van's driver was among those killed. Two other passengers were injured.

The driver did not have a license and his driving privileges had been revoked because of several violations, CHP Officer Eric Erickson said. The driver, from Fresno, had been cited for not wearing a seatbelt, not having a license, and was once arrested for drunken driving. Erickson said there was no conviction for the DUI.

The truck driver, who wasn't injured, had a clean driving record. He was turning his rig around on the two-lane road after parking on the shoulder to sleep, Erickson said. The rig's two trailers were empty.

The van "couldn't avoid hitting the tractor-trailer," Erickson said. "Their brakes locked up."

The van was going at least 55 mph, and the skid marks were 50 to 80 feet long, Erickson said. The accident happened shortly after 5 a.m., just southeast of this tiny town in Fresno County. The laborers had just gotten off work sorting tomatoes in the fields, Erickson said.

In central California's agricultural heartland, farm workers are often transported in crowded vans, which has contributed to a disproportionate traffic death rate among Hispanics in the area.

The highway patrol is so concerned that it has a team focused entirely on vehicles overcrowded with farm workers.

Six officers, dubbed "Los Centinales" -- or "the Sentinels" -- have spent the past three summers patrolling before dawn, stopping trucks and vans of farm workers to check whether the vehicles are complying with state codes.

"We stop those vehicles that are obviously overloaded . . . [where] the back end is sagged down because of the weight of the people," said Sgt. Jorge Chaidez, who runs the unit out of the highway patrol's office in Fresno. "I've seen up to 22 people in a small van."

Dona Portillo, 26, said the van involved in today's crash was owned by her grandfather, Jose Lopez Rosas. He was not in the van, but she said her father was among those killed.

Portillo said she and her mother also had been working in the fields, and the two women had taken a different ride home.

"He told my mom, `You go ahead and go with them, so you can rest and go to sleep,' " Portillo said, sobbing.

One of the injured survivors, a 17-year-old girl, was in critical condition. The other, a man, was in serious condition.

Yolanda Cervantes, who organizes an annual driver safety awareness program in nearby Mendota, said most farm workers have no alternatives but to ride in crowded vans.