esidents of two subdivisions within 1,000 feet of where four chemical tankers derailed Tuesday afternoon.

The decision to impose a mandatory evacuation was made around 4 p.m., while crews worked to right the toppled rail cars, and affected residents of the Acadian Crossing and Sunset subdivisions. Authorities said none of the tanker cars were leaking and described the evacuation as a precautionary measure.

No injuries were reported in the crash, which occurred about 1:30 p.m. just north of the intersection at Peter Messina Road.

West Baton Rouge Parish President Riley “Peewee” Berthelot declared a local disaster emergency later in the day and issued the mandatory evacuation order for those living closest to the derailment as crews work to right the tanker cars and clean up the crash site.

The number of evacuees was not immediately known.

Lynn Cline, a spokeswoman for West Baton Rouge Parish, said 175 to 200 houses were affected, but only those living immediately adjacent to the tracks were evacuated. Other residents were being allowed to shelter in place, she said.

Addis police on Tuesday were going door to door to inform residents and assist with evacuations. They were told the evacuation shelter in place would last throughout the night and possibly until 6 a.m., with no traffic or movement allowed in the area until the righting of the cars is complete.

Cline said the evacuation will not affect La. 1 south traffic as the derailment is at the back of the Addis track. She said La. 1 south will remain open.

Police Chief Ricky Anderson had said shortly after the derailment that it didn’t pose a threat to public safety at that time because “there were no spills or leakage.”

He said the train cars were transporting sodium hydroxide, propylene oxide, propylene dichloride and nitrogen blanket purge.

The Addis Police Department investigated the crash with assistance from the West Baton Rouge Parish Sheriff’s Office.

Anderson said emergency railroad services were on the scene around 3 p.m. to begin the task of picking up the toppled train cars.

The rail cars belonged to various companies but were being pulled by Union Pacific when the accident occurred, Anderson said.

Anderson said authorities believe the derailment was caused by damaged tracks and not operator error.

The train was headed north toward Livonia, he added.

Sodium hydroxide is an inorganic compound used mostly as a chemical base in the manufacture of household cleaners as well as pulp and paper.

Propylene oxide is an organic compound used in the production of polyurethane plastics.

Propylene dichloride is an odorless and flammable organic compound used in the production of perchloroethylene and other chlorinated chemicals.