Fifteen Harris County deputies were exposed to a 'non-toxic irritant' after a release of pressure from multiple small containers holding chemicals at the Arkema plant in Crosby. All were treated and released.

The incident was first reported by emergency officials as two explosions. Law enforcement later began referring to the situation as containers popping, spewing black smoke, and being on fire.

Assistant Fire Chief of Emergency Operations Bob Royall explained in a press briefing these were expected reactions that would lead to fires burning until the organic peroxide in the containers burned out.

Sheriff Ed Gonzalez explained that a number of deputies were in the area establishing a perimeter when the situation unfolded. He said 10 to 15 people, including deputies and personnel from the EMS provider, went to the hospital as a precaution. All were released from the hospital by 9 a.m. Thursday.

Initially, the Harris County Emergency Operations Center notified the company of "two explosions" at the site and also reported black smoke coming from the area around 2 a.m. Thursday.

Asst. Chief Royall explained that they've been consulting with chemists and the company and believe they've developed a safe plan to handle the situation and feel like it will be contained to the facility.

Air monitoring is being deployed to figure out where the smoke might go, and officials say the 1.5-mile evacuation zone is good enough. According to officials, about 200 people in the zone evacuated, but there were still people who refused to leave their homes.

Richard Rennerd, President of Arkema's Acrylic Monomers division, addressed reporters Thursday morning and emphasized a chemical release is not occurring. He warned that inhaling the smoke emanating from the blaze could still pose health risks to the lungs and eyes, "like any fire."

Rennerd refused to outright say whether the chemicals are toxic.

The site contained nine containers of liquid organic peroxide that must remain cold. One of those containers started to degrade Thursday morning. Rennerd says he expects the remaining eight containers to degrade and burn as well.

The plant will allow the fire to burn until flooding recedes.

Rennerd says the plant took several measures, including multiple layers of protection to refrigerate the chemicals. Power was the key source to refrigeration, but the plant also brought in generators, which eventually failed. Liquid nitrogen and refrigerated storage containers were also used.

The nine remaining containers left to burn are at risk of catching fire in three different areas of the plant. Arkema estimates about 1/2 million pounds of liquid chemicals remain. A list of those chemicals can be seen here.

Multiple emergency vehicles, including fire trucks and some boats, were seen heading into the plant evacuation zone after the reported explosions.

Officials had previously said they believed that sometime within the next several days chemicals at the plant would degrade and catch fire because the refrigeration storage and backup procedures had failed.

Government authorities are closely monitoring the situation along with the company.

On Wednesday, Richard Rowe, the chief executive of the company's North America unit, said that while the plant made 'extensive preparations,' a fire would be likely.

A look at the roadblock outside the mandatory evacuation zone surrounding the Arkema chemical plant in Crosby, Texas. 

"The most likely outcome is that, anytime between now and the next few days, the low-temperature peroxide in unrefrigerated trailers will degrade and catch fire."

It appears that outcome is underway and more explosions could occur because the organic peroxide is stored in multiple locations.

"Organic peroxides are extremely flammable and, as agreed with public officials, the best course of action is to let the fire burn itself out," according to a statement from the company.

According to Arkema, the fires will resemble a large gasoline fire. It would be 'explosive and intense' and smoke would be released into the atmosphere and dissipate.

The preparations included having backup generators on site and diesel-powered refrigerated containers to hold the organic peroxide. But all those measures have failed due to flood waters overcoming the entire facility, which is only accessible now by boat.

Rowe further explained that the company doesn't expect to be able to get to the plant until the water around Crosby crests in about 5 to 7 days.

In a statement, the company wrote that there's also a small chance the chemical could release into the flood water and not burn.

Officials said chemical refrigeration at the plant had been compromised due to high water and lack of power.

Employees at the plant were evacuated and families were being evacuated into Wednesday. There are 57 employees who work at the facility.

"At Crosby, we prepared for what we recognized could be a worst case scenario," Rowe says. "We had redundant contingency plans in place."

The plant makes organic peroxides which are used in a variety of things from pharmaceuticals to construction materials. The problem is these organic peroxides can burn if not stored and handled under the right conditions. The company says the fires from the burning organic peroxides will emit a thick black smoke which could irritate the eyes, skin and lungs

“We are monitoring the temperature of each refrigeration container remotely. At this time, while we do not believe there is any imminent danger, the potential for a chemical reaction leading to a fire and/or explosion within the site confines is real," the company said.

The Arkema site in Crosby has been shut-down since Friday in anticipation of the storm. The company says high water in the area is unusual, however.

According to the Environmental Protection Agency, there are about 1,300 households and 3,800 people in a three-mile radius of Arkema. The plant’s chemical inventory includes acetone, benzoyl chloride, chlorodifluromethane, cumene, cumene hydroperpoxide, DI(2-ethylhexyl) phthalate, ethybenzene, ethylene glycol, hydrochloric acid, mercury, methyl ethylketone, n-hexane, sodium hydroxide, sodium sulfate, sulfuric acid and butyl alcohol.