Fire officials say three train cars jumped the tracks behind the Lew Sterrett Justice Center.
Interstate 35E in Dallas reopened around Noon Thanksgiving Day after being closed for nearly four hours. Crews are still working to clean up a 12-car train derailment from overnight, the Dallas Police Department said.
Southbound I-35 was diverted to eastbound Woodall Rodgers. Northbound I-35 was diverted at the Trinity River Bridge. Cars had to exit to eastbound I-30, police said.
Traffic was backed up for at least a mile both ways at one time, according to a Texas Department of Transportation traffic conditions map.
At least 12 train cars jumped the tracks near the Dallas County jail Wednesday night. A Union Pacific train car derailed behind the Lew Sterrett Justice Center at about 7:30 p.m., sparking a chain reaction.
Fire officials said three cars flipped upside down behind the jail.
One of the cars was leaking fluid, but investigators said they do not believe the chemical is hazardous. The cars were carrying cooking oil, fertilizer and plastic pellets.
Hazmat teams have set up a dam at the site of the derailment to keep as much of the chemical as possible from leaking in to the Trinity River.
"Currently, we don't know exactly how much has leaked out, but we do know the capacity is 20,000 gallons, so the potential is a lot worse than the reality, but fortunately, I think we've got it shored up pretty well," Dallas-Fire Rescue spokesman Jason Evans said Wednesday night.
About 7,000 gallons of non-hazardous agricultural fertilizer spilled, Raquel Espinoza of Union Pacific said Thursday.
Fire officials said they believe they've kept the liquid fertilizer from entering Dallas' water system, and they’ll be continuing to monitor the air and water.
“Crews should have the cars re-railed by the end of the day, but we will not have the area clear until next week,” Espinoza said. “The goal is to have everything cleaned up by Monday.”
NBCDFW's Ellen Goldberg contributed to this report.