KATY, Texas (KTRK) -- Authorities lifted a shelter in place that was issued after an overnight chemical leak at a warehouse in west Harris County, according to firefighters.
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The Harris County Fire Marshal's Office said crews responded to a leak at an 800,000-square-foot warehouse in the 23600 block of Colonial Parkway at about 8:42 p.m. on Saturday.
Officials said Hazmat crews were called to the scene after a leak was discovered from an overhead refrigeration line.
About 10 to 12 people who were working on the line at the time of the leak, were evacuated from the building, according to Harris County Fire Marshal Laurie Christensen.
"People were on site when this happened. It became very toxic inside the building and they evacuated and called 911," Fire Marshal C. Shaw said.
At about 1 a.m., the refrigerant, anhydrous ammonia, was no longer contained inside the building.
WATCH: What is anhydrous ammonia? Experts explain
ESD 48 Chief George McAteer said crews could not reach the 16-foot tall line, so experts came in to monitor the air with remote meters once the leak began leaving the building.
"The leak could not be stopped. So we pulled the crews out," McAteer said. "There's a potential for 24,000 pounds (of anhydrous ammonia) in the system."
Harris County Hazmat team was able to enter the warehouse and shut down the generator, and CenterPoint Energy turned off the power, according to Christensen.
On Sunday, the feeder roads north and southbound of 99 at I-10 were reopened after being closed for hours as crews worked to contain the gas. A shelter in place was issued at about 8:30 a.m. and lasted until about 1 p.m.
"There is still some residual inside the building, which is why we're requiring the on-site monitoring until it dissipates," Shaw said. "To ensure this event doesn't happen again, we are requiring them to make all repairs necessary to ensure their system operates as designed."
- Southern boundary: Kingsland Boulevard, between Highway 99 and South Mason Road
- Eastern boundary: Mason Road from Kingsland Boulevard north to Mason Creek
- Northern boundary: Mason Creek from Highway 99 and North Mason Road
- Western boundary: Highway 99 between Kingsland Boulevard and Mason Creek, extending westward
The shelter in place did not include Memorial Hermann Katy.
"We want to make residents aware that they may still smell ammonia, but the levels of ammonia they may smell - we feel confident - are not causing any imminent health risks," Dr. Brown, with Harris County Public Health, said.
If you are experiencing burning, watery eyes, difficulty breathing, and irritation of the nose or throat, authorities urge you to seek immediate care. Ammonia is a clear gas with a strong odor. Officials said it can cause respiratory damage and is toxic. If you smell gas, authorities urge you to contact the Harris County Pollution Control at 713-920-2831.
For fire or life safety hazard complaints, The Harris County Fire Marshal's Office advises people to email firstname.lastname@example.org.
Harris County Pollutions Control has a map where you can track air quality in your area.
WATCH: Authorities give update after chemical leak reported Saturday night at Katy warehouse