Two Canadians are dead and nine remained in hospital after a tour bus in Switzerland went off a straight stretch of road, plunged four metres onto a field and turned over on its side.

Rescuers stand near a bus that went off the road near Reckingen in southern Switzerland, killing two Canadians. (Urs Flueeler/Associated Press/Keystone)

As many as 32 people were reported hurt, but police later said nine were being kept in hospital to treat injuries described as moderate. A Swiss doctor who treated some of the injured said some had broken ribs and bruising.

Police spokesman Markus Rieder said the passengers were mainly retirees from Ontario, but released no names.

The bus, which had German plates, went off the road near the village of Reckingen, about 80 kilometres from the Swiss capital, Bern.

The cause of the crash — going uphill on a dry, straight road in good conditions — has not been determined.

Rieder suggested the driver was distracted by a motorcyclist, "but that hasn't been confirmed yet." The driver, a 73-year-old German, tested negative for alcohol and was reported to be unhurt.

"It's quite an easy road but it's not very wide," said another police spokesman, Pierre-Martin Moulen.

The bus was carrying 48 Canadian passengers, the driver and a guide. Some of the passengers were from Cornwall and some of the seats had been booked through a travel agency in the eastern Ontario city, CBC News has confirmed.

Adele Major's sister and brother, retired Rev. Thomas Villeneuve, were both in the crash. She said they were taking part in what was described as a Grand Alpine Tour, featuring a performance of the Passion Play in Upper Bavaria as well as travel through Switzerland, Austria, Germany and Liechtenstein.

"They're both in hospital; they're in for a few days with minor injuries," Major said from her home in Cornwall. "They were shaken. My brother didn't seem to remember too much, maybe he was knocked out — I'm not sure. He seems to be OK."

A rescue helicopter at the scene of Saturday's fatal bus crash. (Urs Flueeler/Associated Press/Keystone)

The bus was heading from Zermatt, in southern Switzerland, east to Austria.

Survivors of the crash were taken to hotels and offered psychological counselling, said hospital spokeswoman Nicole Bayard.

Friends and relatives seeking information on Canadian citizens believed to be involved can call Foreign Affairs at 1-800-387-3124 or 613-996-8885 (collect calls are accepted), or email sos@international.gc.ca.

With files from The Canadian Press