A petrochemical terminal is on fire at an oil storage facility in Deer Park, Texas just outside of Houston and has been raging throughout the day Sunday. City officials have warned residents to shelter in place and further advised them to close air ventilation systems in their homes and close all windows.

As of 4:30pm central local reports said the fire remains "uncontrolled" and expanded the extent of the shelter in place order.

Image source: The Houston Chronicle

"City of Deer Park issuing SHELTER-IN-PLACE emergency in Deer Park," the city wrote in a tweet at Sunday morning. "Please take immediate action and seek shelter," multiple warnings directed.

In a follow-up warning issued in the afternoon the city said, "Residents are asked to remain sheltered and avoid going outdoors if at all possible. Community air monitoring is being conducted and additional updates will be provided as they become available."

Deer Park Office of Emergency Management issuing a shelter in place for Deer Park. Seek shelter immediately. — City of Deer Park (@DEERPARKTXGOV) March 17, 2019

Still frame of local news coverage at the Intercontinental Terminals Company in Deer Park.

Nearby Pasadena also told residents that Harris County Pollution Control was conducing air quality monitoring tests of the area, and cautioned residents to stay indoors if at all possible.

Firefighters and emergency response crews battled the fire at the Intercontinental Terminals Company in Deer Park, about 15 miles (24 kilometers) southeast of Houston.

Breaking: Massive fire at a chemical plant in Deer Park, Texas. The entire city has been asked to shelter in place. pic.twitter.com/H85ic1JNhp — PM Breaking News (@PMBreakingNews) March 17, 2019

According to the Associated Press:

Harris County officials say the fire started about 10 a.m. at the terminal that stores petrochemical liquids and gases, including fuel oil and bunker oil. The company's website says the terminal has a storage capacity of 13.1 million barrels.

It is the second such petrochemical facility to trigger an area emergency in as many days, per the AP:

The fire is the second in as many days at a Houston-area petrochemical facility. A fire at an ExxonMobil plant in nearby Baytown that broke out Saturday afternoon has been contained. Company officials say no injuries were reported.

Area traffic was gridlocked during the ongoing emergency as major State Highway 225 was closed throughout Sunday afternoon in both directions near the facility.

#Breaking: Just in - Chemical Tank on Fire in Deer Park, at an oil storage facility in #Texas. People are told to stay inside, close air ventilation systems in their homes and close all windows. pic.twitter.com/I4LlisYyJA — Sotiri Dimpinoudis (@sotiridi) March 17, 2019

According to local reports, the chemical tanks that caught fire contain a highly flammable liquid hydrocarbon mixture called naphtha, which is often used as a raw material for production and conversion to gasoline.

Naphtha is classified as "Extremely flammable" and a dangerous irritant to humans if encountered in "high vapor concentration".

According to its chemical safety fact sheet it is "Irritating to eyes and respiratory system. Affects central nervous system. Harmful or fatal if swallowed. Aspiration Hazard."

As of late afternoon southeast Houston area residents were still being warned of the potential chemical hazard due to the petrochemical fire.

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