DEER PARK, Texas (Video above: KTRK via Associated Press) —

Fire erupted at a petrochemical plant in the Houston area Friday, sending nine workers to a hospital and causing a huge plume of smoke visible for miles.

Emergency responders were called to help around 3 p.m. at the Shell facility in Deer Park, a suburb east of Houston. The city of Deer Park said in an advisory that there was no shelter-in-place order for residents.

Harris County Sheriff Ed Gonzalez said earlier in the day that five contracted employees were hospitalized for precautionary reasons, adding that they were not burned. He said they were taken to a hospital due to heat exhaustion and proximity to the fire.

Shell Deer Park officials said on Twitter Friday night that they were continuing to respond to the fire, all workers were accounted for and nine workers had been released after undergoing precautionary medical evaluations.

Nothing exploded, Gonzalez said, although the sheriff's office initially responded to emergency calls saying there was an explosion.

As of Friday evening, the fire was still burning but had died down and was contained, Gonzalez said.

The cause of the blaze was still being investigated. The fire started while the olefins unit was undergoing routine maintenance. Air monitoring for any impact from the fire was ongoing, and had not detected any harmful levels of chemicals, Shell Deer Park said.

"There is no danger to the nearby community," the post said.

The fire started at about 2:56 p.m. in the facility's olefins unit. The product that ignited includes cracked heavy gas oil, cracked light gas oil and gasoline, Shell Deer Park said.

“The cause of the fire will be the subject of a future investigation, and our immediate priorities remain the safety of people and the environment,” facility officials said.

Shell was conducting its own air quality monitoring, but the city has yet to receive an update, said Kaitlyn Bluejacket, a spokesperson for Deer Park.

The city was advised by Shell that there was no need at the time to shelter in place, but that the city would update residents if that changed, Bluejacket said.

Fire crews from the Deer Park facility and nearby plants responded.

Wind conditions were favorable for fighting the blaze, although temperatures soared to near 90 degrees Fahrenheit in the Houston area, but high humidity made it feeler hotter than 100 degrees Fahrenheit.

Harris County Fire Marshal Captain James Singleton said his office would be in Deer Park through the weekend investigating.

“You’re looking at a large number of people that need to be interviewed,” Singleton said. “Everyone who was at the unit at the time of the fire, the controllers, management, anybody that called 911."

Houston meteorologists said the smoke plumes were visible from space via satellite.

Facility fires are not uncommon in the area, with the strong presence of the petrochemical industry. In March, an explosion and a fire erupted at a facility owned by INEOS Phenol in nearby Pasadena, Texas, leaving one injured.

A fire in 2019 at a facility owned by Intercontinental Terminals Company burned for days and though it caused no injuries, it triggered air quality warnings.

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AP writer Lisa Baumann reported from Bellingham, Washington.

GLENCOE, IL — To protect native plant and animal life sometimes requires sustained human intervention. Once brought into the U.S. for its hardiness, the introduction of European buckthorn is out-competing native life across the country.

At the edge of a lagoon in the dead of winter, a group of about two dozen volunteers is braving the icy conditions to save the local ecosystem.

“We're clearing out invasive species with the goal of making room for native species, which are better for the environment overall, but particularly for the amphibians,” said Maggie Cooper, the coordinator of conservation action at Chicago’s John G. Shedd Aquarium.

Cooper is leading the expedition of volunteers focused in part on the resilient and difficult to destroy invasive European buckthorn.

It was introduced into the U.S. as a means for fence farming and for medicinal purposes more than 200 hundred years ago. It’s an aggressive plant that can soak up precious resources and outcompete native plants.

“If you see a stand of buckthorn and you look at the forest floor, you're not going to see anything else growing up. You're only going to see buckthorn growing in that area,” said Cooper.

The plant also emits a toxin called ‘Emodin’ that can kill or suppress the growth of native vegetation.

“Emodin seeps into the soil and we know how amphibians breathe, sometimes they draw in nutrients and their skin,” said Cooper. “And it's known that amphibians will bring that toxin into their body as well. And that can affect their life cycle, especially in the early stages.”

Conservationists have been battling the invader for decades.

It’s now spread across much of the Northeastern, Midwestern, and Western U.S. with some of the most affected states including Minnesota, Wisconsin and New York.

Equipped with loppers and hand saws, the team will clear out as much of the intrusive shrubs and trees as possible.

Stubs are treated with an insecticide to prevent regrowth. Everything is immediately burned.

“If we couldn't have fires, this wouldn't be half as much fun. Not that I'm a pyromaniac or anything, but you know it warms you up,” said Dan Goodwin.

Goodwin has been volunteering with the conservation action group for more than five years.

“From here to the clearing over there [that] edge is two years’ worth of Saturdays and Wednesdays, so you can have an impact,” he said.

Cooper says despite the gains, the work must be constantly ongoing.

“If we just stopped what we were doing, buckthorn is going to come back in,” she said. “So, we need to continue this fight. We need to be out here year after year, month after month.”

It’s an investment of time and labor to protect native wildlife for years to come.