PORT NECHES, Texas (AP) — More than 50,000 people in East Texas remained under a mandatory evacuation order Thursday as a fire continued to burn at a chemical plant, one day after two massive explosions there.

Jefferson County Sheriff Zena Stephens said the evacuation order and a 10 p.m. curfew order remain in effect. Officials don’t know when people will be able to return to their homes.

“It’s Thanksgiving, a lot of people are displaced, they can’t go home,” Stephens told TV station KFDM Thursday, explaining the danger of further explosions and fire rather than air quality problems is the reason the evacuation order remains in place.

The Wednesday blasts, 13 hours apart, blew out windows and doors of nearby homes and prompted a mandatory evacuation of a 4-mile (7-kilometer) radius from the plant in Port Neches in Southeast Texas, about 80 miles (129 kilometers) east of Houston.

Port Neches fire Captain Tyler Herbert said Thursday morning that the fire is still burning and that a mandatory evacuation order covering a 4-mile radius around the plant remains in effect. That order effects 50,000 people, TV station KBMT reported.

At a Thursday evening news conference, officials said the plant is expected to burn into a third day in order to prevent more explosions. He said the plant has 175 full-time employees and 50 contract workers.

The initial explosion at the TPC Group plant, which makes chemical and petroleum-based products, occurred around 1 a.m. It sent a large plume of smoke stretching for miles and started a fire.

The second blast ripped through the plant about 2 p.m., sending a steel reactor tower rocketing high into the air. That prompted Jefferson County Judge Jeff Branick, the top county official, to order a mandatory evacuation of Port Neches and neighboring Groves, Nederland and part of Port Arthur. Water cannons were trained on surrounding plant works and tanks to keep them cool and avoid further explosions.

At a Wednesday night news conference, Branick said a loss of power at the plant prevented any investigation into the cause of the explosions or how much damage was done to the facility. Likewise, he said there was no estimate yet on the extent of damage to surrounding neighborhoods.

Troy Monk, TPC Group’s director of health, safety and security, said the company would form an investigation team to determine what led to the explosions.

“We’re staying focused on the safety of our emergency response personnel folks in and around in the community as well as trying to protect the environment,” Monk said at a news conference.

Firefighters have not been able to fully assess the damage at the plant, he said.

Monk later added that displaced residents can report their hotel costs on a hotline that had been set up to report property damage following the two Wednesday blasts.

Branick, who lives near the plant, said at the news conference that he was awakened at his home by the initial blast, which blew in his front and back doors, “damaging them pretty significantly.”

The three workers hurt during the blast —two TPC employees and a contractor — were treated at hospitals and released, said Monk. The about 30 employees working at the plant at the time of the explosion were accounted for, according to TPC.

Monk had said the blast occurred in an area of the plant that makes butadiene, a chemical used to make synthetic rubber and other products. Officials on Thursday evening, however, said that early concerns about butadiene contamination from the blast haven’t materialized, as they learned the main storage area for that cancer-causing chemical didn’t take the brunt of the fire.

Environmental Protection Agency spokesman Adam Adams said that while volatile organic compounds were detected by some of the 20 teams monitoring air pollution in the area, none of them detected levels higher than five parts per million, the agencies’ “action level.”

Judge Branick, the top county official, told KFDM that it’s a miracle no one died. He said one worker suffered burns and the others had a broken wrist and a broken leg.

Texas has seen multiple petrochemical industry blazes this year, including a March fire that burned for days near Houston and another that killed a worker at a plant in nearby Crosby.

In the March fire, prosecutors filed five water pollution charges against the company that owns the petrochemical storage facility after chemicals flowed into a nearby waterway