Quebec Environment Minister David Heurtel confirmed that five people suffered health problems from the leak and two were sent to hospital, an earlier statement said three people had been hospitalized.
He described the situation in Varennes as "reassuring," and praised the work of emergency services, environmental workers and government officials.
"I can assure you that we are putting all our resources in place to accompany Varennes and its surroundings in this situation," he said at a news conference. "We will be there until the end of the situation."
The leak began Saturday morning following an industrial accident in Varennes, Quebec, about 30 km east of Montreal.
It occurred at the Kronos factory that produces titanium pigment for industrial paint.
Fifteen homes and four factories were evacuated after some titanium tetrachloride was released into the atmosphere.
Kronos issued a statement Saturday afternoon reporting that the leak had been stopped.
"Kronos Canada has implemented all usual environmental emergency and safety rules and procedures to manage the situation," the statement said. "The company is working in cooperation with the environmental and municipal authorities, to take all appropriate measures to protect the population and the environment."
Originally officials estimated that 40 tons of the gas had escaped, but a municipal official in Varennes says it appears only about five tons was released.
A spokesman for the city said that factory employees managed to transfer most of the gas to a secure area.
By late afternoon, Heurtel reported that the toxic cloud was dissipating and that emissions were reduced.
Workers were allowed to enter the factory to begin the cleanup process.
"The process of moving from the emergency stage to managing the situation is clearly underway," Heurtel said.
Titanium tetrachloride when mixed with water can cause symptoms of eye and throat irritation.
The leak drew a large response from police and government officials, including an emergency environmental crew which will continue to monitor emissions in the area until the situation is fully resolved.
A spokesman from Kronos says the cause and exact location of the leak remain unknown.
Note to readers: This is a corrected story, a previous version incorrectly said 40,000 tons of chemical were released