MADERA, Calif. — Seven farmworkers traveling in a van and the driver of a pickup truck were killed Friday in a head-on crash in a farming area in central California, police said.

The crash at 6:15 a.m. left the van almost completely crumpled among blooming almond trees near the town of Madera, about 25 miles (40 kilometers) outside Fresno, California Highway Patrol Officer Javier Ruvalcaba said.

One farmworker seated in the rear of the van survived and was taken to a hospital, Ruvalcaba said. He is expected to recover, Ruvalcaba said.

Only two of the farmworkers were wearing a seatbelt, he said. “If they had been wearing their seatbelts, the rear passengers would have probably survived,” Ruvalcaba said.

A witness told police the black pickup truck was swerving in and out of its lane on a two-lane rural highway before crashing head-on with the van, Ruvalcaba said.

“At this point, we don’t know whether alcohol or drugs played a factor,” he said.

The farmworkers were about 5 miles (8 kilometers) from the vineyard where they worked as pruners when the crash happened, Ruvalcaba said.

The van was headed to the farming community of Firebaugh, an area known for its vineyards and fields of tomatoes, garlic, asparagus and other vegetables.