Kansas City, Mo. ? At least two people remained in critical condition Tuesday after a recreational vehicle crashed in northeast Kansas, killing five family members from Minnesota.

The accident on Sunday injured 13 people. The crash happened as the family returned from an annual motocross vacation in Texas. Their Freightliner cab and Haulmark trailer broke through a guardrail on Interstate 35 outside Williamsburg, Kan., and plunged into a ravine.

The injured ranged in age from 2 to 30 and were taken to various hospitals. Several had been released by Tuesday. The critically injured include an 18-year-old and an 8-year-old boy, who are being treated at two Kansas City area hospitals.

The National Transportation Safety Board also said Tuesday it will be looking into licensing issues involved in the crash.