Updated

A van crammed with farm workers crashed head-on into a truck in central Poland on Tuesday after apparently trying to overtake another vehicle in dense fog, killing all 18 people on board, officials said. The truck driver suffered minor injuries.

The van was designed to carry goods and hold up to six people, yet three times as many were squeezed in on wooden boxes and planks without seatbelts, according to police and a prosecutor.

National police spokesman Mariusz Sokolowski said the collision occurred just after sunrise in thick fog on a slippery road near Nowe Miasto, 50 miles (80 kilometers) south of Warsaw.

"There were many more people in the van than there should be," he said.

The van was apparently trying to pass a third vehicle when the accident occurred, Sokolowski said. Fourteen of the victims were men and four were women.

The passengers were seasonal workers being driven to an orchard in one of Poland's best known apple and plum-growing regions, police spokeswoman Magdalena Siczek-Zalewska said.

Prosecutor Piotr Figas said the van was a Volkswagen Transporter with only six seats, and that the 42-year-old driver was probably the van's owner.

Figas said prosecutors were investigating the crash and examining both vehicles for any technical problems.

Two passengers initially survived with serious injuries and were taken to a hospital, but they both died there. The truck driver was hospitalized with slight injuries and shock, Siczek-Zalewska said.

Authorities called for three days of mourning in the Mazovia region.

The accident follows another serious crash in Germany last month that killed 13 Poles and injured 38. That crash occurred near Berlin when a German woman driving a Mercedes hit a Polish tourist bus returning from Spain.