The Great Gatsby, Tom ran into a wagon

I'd like to know if "wagon" in the following extract from The Great Gatsby refers to a vehicle drawn by horses or a motor vehicle:

That was in August. A week after I left Santa Barbara Tom ran into a wagon on the Ventura road one night and ripped a front wheel off his car. The girl who was with him got into the papers too because her arm was broken—she was one of the chambermaids in the Santa Barbara Hotel.

Thank you.