Police are going door-to-door within several hundred yards of the crash site to either evacuate residents or advise them to "evacuate in place," according to the Baton Rouge Advocate.
Safety officials are planning a "vent and burn" operation to remedy the situation, which involves poking holes in the disabled tanker and burning the fuel on-site.
WAFB-TV reports that the closure has snarled traffic for an entire day in Baton Rouge.
Louisiana State Police Col. Mike Edmonson said authorities will attempt to blow two holes in the tank, ignite the isobutane and conduct a controlled burn. The truck was carrying 8,700 gallons of the chemical.
Police said the accident happened when a car flipped early Wednesday morning after the driver lost control and hit a retaining wall. A tanker truck stopped for the accident and was rear-ended by another 18-wheeler.
Baton Rouge Fire Department spokesman Barry Mounce said the evacuation area will be a few hundred yards around the accident site. Shelters are being set up for evacuees.Photo courtesy WAFB-TV