Authorities warned motorists heading north on I-77 to expect delays Sunday evening after a wreck involving an 18-wheeler near Remount Road.Charlotte Fire Department officials said at least one person was trapped in a vehicle as a result of the crash, which happened shortly before 5 p.m. Firefighters said they were in the process of extracting the patient.It wasn't immediately clear how many vehicles in addition to the 18-wheeler were involved.