Seattle: A school bus carrying international students collided with a tour vehicle in the US West Coast city of Seattle Thursday, killing at least four people and critically injuring 15 others, officials said.
Images of the fiery accident on a busy bridge showed extensive damage to the left side of the bus, part of which was completely sheared off by the force of the crash.
Melissa Mixon, spokeswoman for North Seattle College, told AFP that 45 students and staff with the school`s international program were on board the bus.
She could not immediately provide information on the nationality or age of the victims.
Local news reports said the four killed were all students.
College president Warren Brown told reporters the students were going to visit Safeco Field, a sports stadium, as part of their orientation program.
Seattle Mayor Ed Murray said authorities were assisting families of the victims who were flying into Seattle from several countries.
"The accident occurred when a charter bus traveling with the students collided with a `Ride the Ducks` tour vehicle," Mixon said.
The college hosts some 1,000 international students from 50 countries, including China, Korea and Japan, according to its website.
The school year is scheduled to begin on Monday.
Passengers on board the bus and the "Ride the Ducks" amphibious vehicle -- used for tours in several US cities -- could be seen crawling out of the wreckage, some of them dazed and bloodied, while others were carried away on stretchers.
The "Duck" name is derived from DUKW, which were six-wheel amphibious vehicles used by the US military during World War II.Witnesses said the tour vehicle appeared to have something wrong with its front left tire as it swerved and hit an SUV before crashing into the school bus coming the opposite way.
Bradley Sawhill, who witnessed the crash, told the Seattle Times that everything happened very fast.
"I got out of my car and there were bodies just everywhere," he said. "People lying in the street."
Authorities said in addition to the four fatalities, 51 people were injured in the crash and 15 were in critical condition, including several who were undergoing surgery.
The accident took place shortly after 11:00 am (1800 GMT) on the Aurora Bridge, a busy thoroughfare that links the city`s center with northwest Seattle.
The wounded were transported to area hospitals, which launched an appeal for blood.
Some of the school bus passengers who escaped relatively unscathed were taken to the nearby Woodland Park Zoo where they were given first aid before being taken back to their campus.
Other bloodied victims were laid out on yellow tarps near the scene of the accident.
Murray said his thoughts and prayers were with the victims and their families.
"Seattle had a terrible tragedy today," he said in a statement. "There has been loss of life and dozens of injuries."
Seattle police said an investigation was under way to determine the cause of the crash and a team from the National Transportation Safety Board was expected in Seattle Friday.
"Collision investigators are reviewing witness reports of a possible mechanical issue on the Duck vehicle," a statement said, adding that preliminary alcohol tests on the drivers came out negative.