PROVO — A trailer fire shut down I-15 in both directions for a short time during the Wednesday evening commute.

The 20-foot U-Haul trailer was carrying some property, but mostly empty boxes when it caught fire south of the Center Street exit around 5:20 p.m., said Utah Highway Patrol trooper Cameron Roden.

Traffic was stopped in both directions for a short time because of heavy smoke. All but one northbound lane were reopened by 6 p.m.

Officials believe a mechanical malfunction was likely what sparked the blaze, but the official cause is still under investigation. No one was injured.