The Jefferson County Sheriff's Office says the accident Thursday morning, during fog and smoky conditions, happened on Highway 73, about five miles west of Port Arthur.
Deputy Rod Carroll says smoke from recent nearby marsh fires contributed to the crashes around 5:45 a.m. Thursday. The highway reopened about five hours later.
Carroll told The Associated Press that 54 people were injured, with many treated for broken bones, abrasions and trauma. He says one of the four critically injured motorists suffered an apparent heart attack after the wreck.
The victims were transported to Port Arthur and Beaumont hospitals. Further details on their conditions were not immediately released.