The explosions in Port Neches follow two fires near Houston at petrochemical facilities, including one that killed one person and critically injured two others. The blasts also come just after federal environmental officials eased rules enacted after a deadly explosion at a fertilizer plant in West, Texas, in 2013, which was one of the state’s worst industrial disasters.

In Port Neches, the first blast happened just before 1 a.m., erupting into a ball of fire that lit up the night sky. The explosion shattered windows and even blew out doors. Then, on Wednesday afternoon, a second explosion rocked the plant, shooting a flaming tower into the air like a rocket.

The authorities said on Thursday that firefighters had made considerable headway in containing the fire, but it was not enough to lift the evacuation order. It was also unclear how long the fire would burn.

“We’re not out of the woods yet,” Judge Jeff Branick, the top elected official for Jefferson County who is overseeing the response, said at the news conference on Thursday afternoon. “I think there’s been very significant progress that has been made. But I want to tell you, my job as county judge is to keep our citizens safe.”

On Thursday, the neighborhoods around the plant were dead quiet as black smoke continued to billow into the air. Some streets had been blocked off and an abundance of law enforcement officers were on patrol, telling curious onlookers and residents to get going.

The plant sits in a tangle of communities — including Port Neches, Groves and Nederland — where suburban neighborhoods and industry are wedged together.

The blasts riled an area that had endured devastating floods in September, as well as Hurricane Harvey in 2017. The disruption was an unwelcome reminder of the routine evacuations that come during hurricane season, when residents have to load up and head north.