It's been burning since around 10 a.m. Monday.
Investigators believe it was all sparked by a car that crashed into an above-ground pipeline valve off Spencer Highway.
ORIGINAL REPORT: Deer Park pipeline burnoff estimated to last through early Tuesday morning, company says
Police trying to identify driver of SUV involved in pipeline fire
Harris County Judge Linda Hidalgo said once the fire is out, first responders will try to re-ignite the site to burn off any remaining product.
In an update on Tuesday morning, the Deer Park Office of Emergency Management said the fire is significantly smaller, but extended the expected burn-off timeline through later Tuesday.
Energy Transfer, the company that owns the pipeline, said air quality monitoring continues to show no impact to air quality.
Evacuees who were transported from the Walmart parking lot can now return to pick up their vehicles. Officials have asked all evacuees to travel southbound on East Boulevard to meet at the checkpoint. From there, you'll be escorted to your vehicle and you can exit northbound from the parking lot.
SkyEye video showed the flames continuing to burn on Tuesday morning.
Officials said first responder crews worked all through the night, with the goal of isolating the fire and letting it burn itself out.
Authorities believe the driver of a white SUV drove through a fence on the west side of the nearby Walmart parking lot in the 9000 block of Spencer Highway, hitting the pipeline valve.
Witnesses told ABC13 that when the SUV hit the gas pipeline valve, it went airborne, then came the flames.
SEE ALSO: Deer Park pipeline blast witnesses describe airborne SUV: 'The car goes up in the air and back down'
Couple witnesses crash that ignited pipeline: 'Car goes up in the air'
The resultant explosion started in Deer Park and then spread south under Spencer Highway to La Porte, as the highway separates Deer Park to the north and La Porte to the south.
Witnesses said they believe the woman driving the SUV was possibly experiencing some kind of medical emergency.
Further details about the driver and her condition have not been released.
Witness Hank Williams said he was at a nearby Discount Tire when he heard a loud boom.
"I stepped around the counter and I could see the vehicle and it was on fire," Williams said. "He said when it went off, he saw that vehicle go about 8 or 10 feet in the air and then he saw it land."
Officials said the area will have to cool down before residents can return to their homes. Around 50 homes near the fire had to be evacuated.
Energy Transfer identified the burning substance as liquid natural gas. In the wake of the event, the company set up a helpline for anyone displaced and/or impacted by the fire at 855-430-4491.
A Deer Park official told ABC13 that four people were injured from the event, including a firefighter for minor injuries. The four also includes two hospitalizations and two heat-related injuries.
Classes continued as usual on Tuesday morning in La Porte ISD after two elementary schools had to shelter in place on Monday.
The district asked parents who live in the evacuation zone to drive their kids to school on Tuesday, if possible. The district said its transportation department is working on other plans for kids who will need to ride the bus.
13 INVESTIGATES: Energy Transfer waits hours before providing info on pipeline fire
Energy Transfer waits hours before providing info on pipeline fire