Harris County sued Exxon Mobil on Thursday, moving aggressively to enforce environmental laws one day after the company’s Baytown plant erupted in flames and injured at least 37 people.

The suit alleges that the company violated the Texas Clean Air Act when its Olefins plant, where the fire broke out following an explosion, released unauthorized emissions into the atmosphere. It seeks a temporary injunction ordering Exxon Mobil to comply with the Clean Air Act, the Texas Water Code and the Texas Administrative Code.

“We filed this morning even though the fire is out because we need to be sure the case is handled by a Harris County court,” said Rock Owens, managing attorney for the Harris County Attorney’s environmental section.

The county also sued Exxon in March for alleged violations at another of its Baytown plants after a fire.

Exxon Mobil did not respond to a request for comment Thursday.

“Filing these suits very quickly sends a very clear signal to violators that their actions are seen and are in violation of the law and will be prosecuted as crimes, and I think that that is an important message to get out,” said Adrian Shelley, the director of the Texas office of the consumer advocacy group Public Citizen. “It’s just as important to follow through.”

Shelley said Texas Attorney General Ken Paxton has also been quicker to file lawsuits against chemical companies — likely in response to Harris County. But advocates, he said, have a “wait-and-see” attitude about state action, suspecting it might preempt more aggressive moves on the county level.

Just as important, said University of Houston environmental law professor Victor Flatt, is that the suit seeks to establish jurisdiction in Harris County. If the county clears that hurdle successfully, it can move much faster in the event of another petrochemical incident.

“When a court has jurisdiction, a court can more quickly impose penalties and hold them (polluters) in contempt,” Flatt said. “It means they can have more aggressive fines and more quickly control any future action.”

Under the state Clean Air Act, the county may impose penalties of $25,000 per day per violation. Although Wednesday’s fire was a one-day event, it likely caused multiple emissions. Penalties can be much higher if a company violates a court order.

“They’re seeking an injunction to get a judge to order them to stop these violations from continuing to happen, and that’s where we can see some really meaningful progress,” said Luke Metzger, executive director of Environment Texas, an environmental advocacy organization. “Exxon’s been breaking the law and polluting for years.”

In a lawsuit against Chevron and Shell, Environment Texas won an injunction that forced the companies to reduce emissions by 80 percent over three years or face automatic penalties. An injunction against Exxon could allow the company to meet such a goal on its own, Metzger said, or lay out specific steps it needs to take.

The Exxon Mobil fire is the fourth petrochemical fire in the Houston area in 2019. Just after Exxon Mobil’s Baytown fire in March — which leaked pollutants into the air for eight days — the Intercontinental Terminals Co. plant in Deer Park burned for three days. After the ITC fire, Harris County Commissioners Court authorized the county attorney’s office to file environmental cases without the court’s approval.

Thursday’s case is the first filed with the new authority.

In another signal that the county is looking to crack down on environmental violations, the Harris County District Attorney’s office asked the county to triple the number of prosecutors focused on polluters.

“I hope through the county’s action, we can get Exxon to finally invest some money and take the steps and pay attention to prevent these violations from happening,” Metzger said. “It’s a marked change from previous years where the county was very slow to act.”

A fire in early April at the chemical plant KMCO in Crosby — this year’s third petrochemical incident in the region — killed one worker and injured five more. Two workers filed suit, as did Harris County.

Exxon Mobil’s three plants in Baytown have a history of environmental violations.

A company statement noted that Exxon Mobil spent nearly $1 billion on the Baytown complex since 2005 to improve environmental performance. But the investment came after a lawsuit by the Environmental Protection Agency.

The cause of Wednesday’s fire, which began shortly after 11 a.m., is still unknown. Exxon Mobil officials said it began in an area used to purify the chemical propylene, which is used as a fuel and in making plastics.

A company spokesperson said that as of Thursday morning, “all workers who received medical evaluation or first aid have been cleared to return to work.” The injuries were minor burns, plant manager Jason Duncan said.

Harris County air monitors have not so far shown toxins at a dangerous level.

Ricky Brooks, president of the United Steel Workers Local 13-2001 union in Baytown, was working in the Exxon chemical plant, separated by fencing from the Olefins plant where the fire occurred.

“These events really drive home how inherently dangerous these jobs really are,” Brooks said. “By the grace of God we had 37 injuries and not 37 fatalities.”