@SLO_City_Fire and working hard to contain multiple rail car fires in SLO. Suspicious origin. Cars full of used railroad ties. pic.twitter.com/JLS5k7cfaa

— SLO City Fire (@SLO_City_Fire) May 16, 2018

Multiple train cars caught fire in San Luis Obispo early Wednesday morning, causing a blaze that burned for several hours and possibly released hazardous chemicals into the air. San Luis Obispo fire officials say they are not ruling out arson as the cause of the fire.

The train cars were full of used railroad ties, according to the San Luis Obispo Fire Department. Railroad ties tend to be soaked in creosote, a toxic chemical.

At about 3 a.m., the fire broke out on train tracks near Orcutt Road and Laurel Lane. The blaze continued to burn after sunrise despite efforts by firefighters to extinguish it.

Fire officials said they did not expect the blaze to be extinguished until mid-morning. Witnesses said the fire created a strong stench in the area.

There are no road closures, but drivers are requested to avoid the area of the fire. At least one train trip was cancelled as a result of the blaze.

There have been no reports of injuries.