Health and security officials have stopped the leak of titanium tetrachloride at the Kronos chemical plant in Varennes, just outside of Montreal.

Kronos produces pigments and chemicals at its Varennes, Que., facility. (Radio-Canada)

Varennes fire Chief Alain Pharland said employees inside the plant have diverted the contents of a leaking reservoir to another container.

Officials first learned of the leak at 10:15 a.m. ET on Saturday.

Homes within 400 metres of the plant on Marie-Victorin Road have been evacuated, and a confinement order is in effect for people living between Côte Bissonnette Road and Montée de la Baronnie.

Le nuage émanant de l'usine <a href="https://twitter.com/hashtag/Kronos?src=hash">#Kronos</a> de Varennes vu depuis Repentigny Photo TC Media Stéphane Grégoire <a href="http://t.co/6iVPhWR9RW">pic.twitter.com/6iVPhWR9RW</a> —@hebdorivenord

5 people being treated

Five people were being treated for injuries after the leak.

Three of the five were workers at a nearby factory and have been transported to the Pierre-Boucher Hospital for treatment. Their condition is unknown.

Another two were area residents, and have not been hospitalized.

Authorities checking air quality

Kronos makes pigments and other chemicals at its Varennes plant. Titanium tetrachloride is often used to make titanium dioxide, a main ingredient in paint.

Authorities said the leak was caused by a break in equipment.

An official with Quebec's Urgence-Environnement is on the scene and the TAGA mobile lab is taking air samples.

Dr. Eric Lévesque said people exposed to the hydrochloric acid could experience irritation in the eyes, nose and lungs. (Radio-Canada)

Titanium tetrachloride, when mixed with water, turns into hydrochloric acid. Because of the water content of Saturday's snow, a white cloud of the latter substance formed over Kronos.

People living outside the affected zone may detect a particular smell in the air.

The environment ministry issued a statement Saturday saying that it is taking all measures and precautions necessary to ensure the safety of the population.

What are the dangers?

People's reactions to hydrochloric acid depends on the concentration they're exposed to, Dr. Eric Lévesque said at a news conference Saturday afternoon.

He said the likelihood of anyone experiencing any major symptoms is slim because people were removed from the area early on.

According to the American Environmental Protection Agency, hydrochloric acid is "corrosive to the eyes, skin, and mucous membranes. Acute (short-term) inhalation exposure may cause eye, nose and respiratory tract irritation and inflammation and pulmonary edema in humans."

Titanium tetrachloride, according to the EPA, is used in a variety of products, including in the production of titanium metal, titanium dioxide, and titanium pigments.

People exposed to the compound may experience difficulty breathing or a burning sensation in the eyes or on the skin.

The EPA says it has a "penetrating acid odour," and that it has not been linked to cancer.