Authorities on Thursday lifted a shelter-in-place order hours after warning people to stay indoors because high levels of benzene were detected in the air near a scorched petrochemicals storage facility outside of Houston. Officials in Deer Park, Texas, said there was a sustained period of improved air quality readings in the area and lifted the order late Thursday morning.

Firefighters on Wednesday extinguished the blaze at the Intercontinental Terminals Company in Deer Park, which started Sunday and destroyed several large tanks that contained gasoline and chemicals used in nail polish remover, glues and paint thinner. They continued to spray foam on the site Thursday to try to prevent flare-ups.

Officials said Wednesday that benzene levels near the facility didn't pose a health concern. But authorities issued the shelter-in-place order early Thursday due to "reports of benzene or other volatile organic compounds" in Deer Park, which is about 15 miles southeast of Houston.

Get Breaking News Delivered to Your Inbox

Several school districts also canceled classes for the day due to the air quality concerns. Harris County Judge Lina Hidalgo, who is the county's top administrator, said at a news conference Thursday morning that light winds were helping to keep the vapors from spreading more broadly.

The county fire marshal, Laurie Christensen, said the benzene vapors may have been escaping from gaps in the foam that firefighters have been spraying to try to prevent flare-ups at the site. The Texas National Guard's 6th civil support team was assisting at the scene Thursday.

Area affected by shelter-in-place order around ITC plant in Deer Park, Texas early on March 21, 2019 KHOU-TV

The team of about a dozen was helping to contain hazardous materials and provide other assistance to local emergency responders. Environmental groups said residents who live near the facility have experienced various symptoms, including headaches, nausea and nose bleeds.

According to the Centers for Disease Control and Prevention, long-term exposure to the highly flammable chemical causes harmful effects to blood, including bone marrow. The Environmental Protection Agency conducted air quality tests throughout the Houston area, both on the ground and from a small airplane, and "measured no levels of hazardous concentrations," EPA official Adam Adams said Wednesday.

Some residents who live near the facility, though, said they didn't have confidence in the air quality test results. "I do not fully trust what they say," said Kristin Crump, who lives with her husband and two children less than two miles from ITC. "I do believe what is in the air is very harmful and it can have long-term effects such as cancer and things like that later down the line. I don't think it's worth risking that for me or my kids to stay there and breathe in this stuff."

Crump, 31, placed damp wash cloths over her mouth and those of her 13- and 6-year-old children Thursday as they walked to their car to go stay with family elsewhere. Her husband later joined them.

The family also left the area Tuesday after the children complained of headaches, she said. They returned the next day.

Bryan Parras, an organizer in Houston with the Sierra Club, said his environmental group had concerns not just about the air quality, but about the potential impacts to the environment and the fishing industry if chemicals from the storage facility or firefighting foam get into the Houston Ship Channel, which leads to the Gulf of Mexico. "This issue isn't over just because the fire is out. We want systems in place that will protect our communities," Parras said Wednesday.

The EPA and the Texas Commission on Environmental Quality said Wednesday that they were waiting for test results of water samples to determine any potential impacts from the foam used to fight the fire on waterways next to the storage facility, including the Houston Ship Channel.