A pipeline fire that burned in a Houston suburb for four days finally went out Thursday as authorities announced a criminal investigation into the blaze that had roared into a towering flame, forcing neighborhoods to evacuate and melting parts of nearby cars.

Before the fire fully stopped Thursday evening, officials announced that human remains were found in an SUV that had been next to the flame since the explosion happened Monday. Investigators say the fire began after the driver of that car went through a fence alongside a Walmart parking lot and struck an above-ground valve.

Officials in Deer Park, where the explosion occurred, described the crash as an accident, and said police and local FBI agents have not found evidence of a coordinated or terrorist attack.

“This has developed into a criminal investigation and will be actively ongoing until more information is available,” the city said in a statement late Thursday.

As authorities worked to identify who had driven the vehicle, residents who were forced to flee the towering blaze returned to assess the damage on Thursday. They found mailboxes and vehicles partially melted by the intense heat, a neighborhood park charred and destroyed and fences burned to the ground.

“Devastated, upset, scared. We don’t know what we’re going to do now,” said Diane Hutto, 51, after finding her home severely damaged by water that firefighters poured on it to keep it from catching fire. Hutto’s home is located only a few hundred feet from the pipeline.

Before the fire went out, its reduced size meant police finally had access to the area around the pipeline. Investigators removed the white SUV and towed it away Thursday morning.

While medical examiners with Harris County were processing the vehicle, they recovered and removed human remains found inside, Deer Park officials said in a statement.

Officials say the underground pipeline, which runs under high-voltage power lines in a grassy corridor between the Walmart and a residential neighborhood, was damaged when the SUV driver left the store’s parking lot, entered the wide grassy area and went through a fence surrounding the valve equipment.

But authorities have offered few details on what caused the vehicle to crash through the fence and hit the pipeline valve.

Energy Transfer, the Dallas-based company that owns the pipeline, on Wednesday called it an accident. Deer Park officials said preliminary investigations by police and FBI agents found no evidence of a terrorist attack.

The pipeline is a 20-inch-wide (50-centimeter-wide) conduit that runs for miles through the Houston area. It carries natural gas liquids through Deer Park and La Porte, both of which are southeast of Houston.

Authorities evacuated nearly 1,000 homes at one point and ordered people in nearby schools to shelter in place. Officials began letting residents return to their homes on Wednesday evening.

Hutto said Thursday the fire incinerated her home’s backyard fence and partially melted a small shed where her husband stored his lawnmower. Inside the home, mold and mildew were starting to set in from the water damage, and part of the ceiling in her daughter's bedroom had collapsed.

“Everything is just soaking wet,” she said. “It smells bad. I don’t think there’s really anything we can salvage at this point.”

Across the street, Robert Blair found minor damage when he returned to his home Thursday morning. It included broken and cracked windows and a window screen and irrigation system pipes that had been melted by the heat.

“We were very lucky here. It could have been worse,” said Blair, 67.

The pipeline’s valve equipment appears to have been protected by a chain-link fence topped with barbed wire. Energy Transfer has not responded to questions about any other safety protections that were in place.

Harris County Judge Lina Hidalgo, the county’s top elected official, said Thursday that officials will look at whether they can require companies like Energy Transfer to install better security measures, including concrete structures around pipelines and their aboveground valves.

“If they had that around it, I don’t think this would have happened,” Blair said.

Energy Transfer and Harris County officials have said that air quality monitoring showed no immediate risk to individuals, despite the huge tower of billowing flame that shot hundreds of feet into the air when the fire first began, creating thick black smoke that hovered over the area.

Houston, Texas’ largest city, is the nation’s petrochemical heartland and is home to a cluster of refineries and plants and thousands of miles of pipelines. Explosions and fires are a familiar sight in the area, including some that have been deadly, raising recurring questions about the adequacy of industry efforts to protect the public and the environment.

Hidalgo said some residents she spoke with told her they don’t feel safe living in the area after this week’s fire.

Hutto, whose husband works in a petrochemical plant, said living near such facilities has always been a concern, but this week’s fire has changed things for her.

“I don’t think I want to live here anymore. I’m just too scared to stay here,” Hutto said.