A boat carrying mostly American tourists on a sightseeing trip down the Danube River rammed a landmark bridge in Vienna on Thursday, injuring at least 19 people, authorities said.

The MS Viking Europe tour boat struck into a piling on the Reichsbruecke (search) bridge, one of the main spans carrying traffic over the Danube in central Vienna. The boat was carrying 135 passengers, 129 of them Americans, authorities said.

The rest were Britons and Canadians, and the boat was manned by a crew of 39.

Initial reports said 20 passengers were seriously injured, but police Col. Robert Haas later said 19 were hurt and their injuries were minor, mainly scratches and bruises. One of the injured was a cook who suffered light burns, Haas said.

The injured were brought to a hospital for treatment, rescue officials said.

The Reichsbruecke bridge is a popular landmark in Vienna (search) often photographed for its dozens of ornate lamps. It was not seriously damaged, officials said.

The boat had begun its journey in the quaint Danube town of Duernstein, about 50 miles west of Vienna, and was preparing to swing around to return to the river's main branch when it struck the bridge, Haas said. The Vienna navigation authority said the stern of the boat rammed the bridge at about 8 a.m.

The collision damaged the restaurant deck of the boat, which was packed with tourists enjoying a bright, sunny morning.

Investigators said the second officer, and not the boat's captain, was at the helm when the accident occurred. The officer was said to be distressed and was being treated by psychiatric experts, APA reported.

The German company that operated the boat, Klaus Saar GmbH (search), said it was sending a technical expert to evaluate the damage and aid the investigation. The vessel was built in 2001, the company said.

Dozens of tour boats ply the Danube daily, carrying thousands of tourists through the Austrian capital. Serious accidents are relatively uncommon. The worst recent accident happened in October 1996, when a Slovak tour boat foundered in floodwaters and sank, killing eight Slovak tourists.

The span links the United Nations complex to Vienna's downtown, and it has become synonymous with the Vienna City Marathon, which is run over the bridge.