GRENOBLE, France - A bus carrying Polish pilgrims from a holy site in the French Alps plunged off a steep mountain road, crashed into a river bed and burst into flames Sunday, killing 26 people, authorities said.

View of the wreckage of a bus that was transporting Polish pilgrims from a holy site in the French Alps, after it plunged off a steep mountain road, crashed into a river bank and burst into flames, Sunday, July 22, 2007 by the Romanche river in Vizille, south of Grenoble, killing 24 people, authorities said. [AP]

Another 20 people were seriously injured in the wreck, which occurred at about 9:30 a.m. near the village of Vizille, not far from Grenoble, officials said.

Firefighters said the bus had 51 people on board, including the driver, and plowed through a barrier before it plunged about 65 feet onto the banks of the La Romanche River, firefighters said.

Residents of Notre-Dame-de-Mesage, a town near the site, said the bus missed a 90-degree bend in the steep mountain road. They said the bus burst into flames and was destroyed in the blaze.

Buses have been prohibited from using the 5-mile stretch of road - which has a 7 percent grade - without a special permit since a similar accident in the 1970s, also involving pilgrims.

The bus involved in Sunday's crash pilgrims had no such permit, firefighters said.

News footage showed the charred remains of the bus, with wreckage strewn across the river bank.

Victims were evacuated by helicopter to hospitals in Grenoble. Others with light injuries were being treated in a field nearby.

A handful of missing passengers may have been thrown out of the bus and into the river, firefighters said. Crews were searching the river by helicopter and boat.

The pilgrims were returning from the shrine of Notre-Dame-de-la-Salette, about 25 miles south of Grenoble.

The prefecture of the Isere region in southeastern France said 49 passengers, a driver and another person - likely a second driver - had been on board the bus.

Marcin Szklarski, president of the trip's organizer, Orlando Travel, told Poland's TVN24 television that the pilgrims, aged 40-60, were from Szczecin and surrounding towns in the northwest of the country.

The group left Poland on July 10 on a two-week visit to famous sanctuaries in France, Spain, and Portugal, including shrines in Lourdes, France and Fatima, Portugal, Szklarski said.

The bus, a 2000 Skania, passed safety inspection checks three weeks ago in Germany, Szlarski said.

Szlarski said 50 people were on the bus: 47 pilgrims, two drivers and a guide.

French President Nicolas Sarkozy expressed his condolences to his Polish counterpart, Lech Kaczynski, in a letter Sunday.

"During this ordeal, you have the solidarity of the French people," Sarkozy said.

Though it rained heavily on Saturday night, weather in the region was warm and sunny on Sunday and the road was dry.

French Prime Minister Francois Fillon was to visit the crash site later Sunday.

Nestled between Alpine peaks, the Sanctuary of Notre-Dame-de-la-Salette is about 5905 feet above sea level. The complex was built on the site two local boys claimed the Virgin Mary appeared to them in 1846. It has since become an important pilgrimage site, drawing Catholics from around the world.