Around a thousand Oklahoma residents were evacuated from their homes after a terrifying chemical leak blanketed the area.

Locals in Weatherford, located about an hour outside of Oklahoma City, were awoken by gas-mask clad police hammering on their doors early Thursday.

As they were urged to flee their homes, 600 other people were directed to shelter-in-place after an 8,500-gallon Airgas tanker truck crashed and leaked anhydrous ammonia gas in a Holiday Inn Express parking lot, officials said. 

The crash happened around 10pm Wednesday before the truck driver parked the damaged trailer behind the Holiday Inn and spent the night at the hotel, Weatherford Police Chief Angelo Orefice said.

At least 36 people were rushed to a nearby hospital after experiencing respiratory distress. 

Eleven of them were transferred to hospitals in Oklahoma City’s metro area in critical condition, officials said. 

Anhydrous ammonia, a colorless gas with a strong odor, is commonly used as a fertilizer that helps provide nitrogen to wheat and corn plants. 

But contact in either gas or liquid form can cause severe burns, respiratory issues, and irritation to the eyes, skin and throat.

The cause of the leak remains unknown, but officials are treating the incident as an accident. 

Residents were also evacuated to Southwestern Oklahoma State University’s Pioneer Center while a shelter-in-place was issued for 500 to 600 people. It has since been lifted. 

Several residents, including two people who were staying at the hotel, described the frightening scene after being told the toxic chemical was in the air.

‘I smelled, my door was closed, so it wasn’t coming in a high volume, you know, toxic smell to the room,’ a man told News 9. ‘But I smelled something was wrong.’ 

Another male resident also described the horrible smell. 

‘It was a spicy smell, very spicy smell. We went out from the room and we saw people over there, you know, they were telling us they were also coughing,’ he recalled. 

‘So I understand something [was] wrong over there.’ 

Schools, including Southwestern Oklahoma State University, were closed for the day and several nursing homes in the area were evacuated. 

The tanker truck is no longer releasing gas and authorities are monitoring the city’s air quality. 

The west and eastbound exits of I-40 remained closed as of Thursday morning as response to the leak continues. 

Local businesses affected by the leak had to have their air quality checked by the fire department before opening their doors again, Orefice said. 

The police chief said the clean up from the chemical spill could take days. 

‘We’ve pretty much got a lot of this stuff diluted right now,’ Orefice said, adding that officials were working alongside the Environmental Protection Agency to figure out how to get rid of the chemical completely. 

Airgas, an industrial gas distributor, told the Daily Mail it was working with local authorities to respond to the chemical spill.

‘We are working with local authorities to respond to an incident in Weatherford, Oklahoma involving an anhydrous ammonia release from an ammonia transport trailer,’ a spokesperson with the Pennsylvania-based company said. 

‘Our top priority is the safety and well-being of the local community and the first responders on-site.’

The Daily Mail contacted the city of Weatherford and the Weatherford Police Department for comment.