Chlorine gas Chicago attack in the hotel sickens 19 people and led to thousands of people being evacuated on Dec. 7 during the Midwest FurFest convention. Police authorities have concluded the incident as an "Intentional Act."

The Chlorine gas Chicago attack at Hyatt Regency O'Hare in suburban Rosemont happened around 12:40 a.m. when a toxic odor was smelled on the ninth floor of the hotel. The Rosemont Public Safety Department discovered high presence of chlorine gas in the air, the Chicago Tribune reports.

19 people were rushed to nearby local hospitals after they felt sick with complaints including dizziness, nausea and other health problems. Thousands of participants were taken on nearby buildings. All the rest reported no complaints on their health.

The event "Midwest FurFest" was being held in the hotel, a weekendlong convention that focuses on art, literature and performance based on anthropomorphic animals based on Midwest Furfest website. The chlorine gas Chicago attack targeted those participants dressed in animal costumes.

"I think we'll recover from this," said Kit McCreedy, a 28-year-old from Madison, Wisconsin, who is dressed in fox costume in the last day of the Midwest FurFest. "People are tired but they're still full of energy."

Chlorine gas Chicago attack was found to be intentional when investigators discovered chlorine powder spilled out on the stairwell on the ninth floor of the hotel. Technicians were able to decontaminate the area and convention-goers were allowed to return after two hours.

Participants in the Midwest Furfest convention were curious on who did the trouble in the hotel. The event that is held every year includes fun and learning activities such as panel discussions and dance contests.

Some of the attendees like Thomas Zell of Arlington Heights said that he and his friends were near the hotel entrance at the convention when he suddenly spotted people leaving the area and crowding outside the hotel. He added similar hoax incidents are very common during Furry events.

Other convention goers Morgan Smejkal and Chris Delaney of Iowa reported that they didn't hear the alarm in the building. They said that they just heard about the evacuation from his friends who texted and from the hotel staff.

Some people expressed their opinions on the Chlorine gas Chicago attack in Twitter with hashtag #ChlorineGasIntentional and #chlorinegas

I've always feared this "police say it appears that "an intentional act" was behind high levels of chlorine gas"

_Shoq (@Shoq)

"I'm not trying to shame folks, but furries are human beings; chlorine gas is extremely dangerous; police say probably intentional act."

_Glenn Fleishman (@GlennF)

"A possibly-intentional chlorine gas leak at a hotel is a notable story even if the hotel isn't hosting a furry convention."

_Josh Barro (@jbarro)

Chlorine gas Chicago attack had triggered 19 participants to be sick from inhaling the toxic substance. Police investigators concluded the incident as a criminal offense. Authorities are still searching for the one responsible for the chlorine gas Chicago attack.