I strongly recommend that you take at least one class while working as an intern. My suggestion to you is to contact local engineering firms to express your interest in getting an internship/temporary position with them. It would also be great if you consider involvement at local levels of some of the engineering organizations such as, the American Society of Engineering Education (ASEE), the American Society of Civil Engineers (ASCE) American Society of Mechanical Engineers (ASME), Biomedical Engineering Club (BMEC), etc…. Attending their monthly meetings would be a great step because there is a lot of value in attendance and involvement.
Other ways would be to attend Career Fair events that local Engineering schools are hosting each semester. The career fair event is a great opportunity to develop a network of contacts, meet and talk with representatives from a broad spectrum of companies, and learn about potential internship opportunities. I also think that attending one of the below summer engineering programs can also be a great way to explore the engineering field and also again experience.
The American Public Transportation Foundation (APTF) members have put together an internship database for students who would like to get an internship in the transportation field. So, here is the link.
I hope this helps.