The crash occurred at a railroad crossing at Midland in West Texas last evening, Midland police chief Price Robinson said, adding many of the injured appeared to be veterans and their spouses.
Two persons died at the spot and two others died at a hospital, Robinson said.
At least 10 victims were in a critical condition while seven were stable at Midland Memorial Hospital, he added. "The event was to honour military heroes and their spouses," said Robinson.
The parade, led by a local group called Show of Support, was supposed to take the veterans through the city before ending at a banquet. The group provides outdoor opportunities for wounded service members, claims its website.
The National Transportation Safety Board said it has launched a probe into the crash.
