MONTREAL -- The return to power of the separatist Parti Québécois continued to be overshadowed on Wednesday by a shooting here that the police said might have been an assassination attempt on Quebec's premier-designate.
The shooting, which killed one man and critically injured another shortly before midnight Tuesday, was followed immediately by a firebombing at the concert hall where the party's victory celebration was being held.
The Montreal police initially described the shooting as a homicide, but said Wednesday that it had been upgraded to "a crime against the state."
"There is a possibility someone was attempting to take the life of" the Parti Québécois leader, Pauline Marois, said a Montreal Police Service spokesman, Sgt. Laurent Gingras.
The shooting, which appeared to be related to the gunman's dissatisfaction with laws requiring the use of French in Quebec, smothered the festive mood in the downtown concert hall where Ms. Marois was celebrating the high point of her political career, which began in the late 1970s.
The Parti Québécois won 54 of the 125 seats in Quebec's provincial assembly, but was still well shy of a majority.
To loud cheers from her supporters, Ms. Marois vowed that she would work to separate Quebec from the rest of Canada. But after she stated her "firm conviction that Quebec needs to become a sovereign country," the hall fell into stunned silence as two plainclothes police officers abruptly pulled her from the stage.
The police said that a man with a gun and a pistol entered the hall through a back door near the stage and shot two men; Denis Blanchette, 48, a stagehand at the hall, was killed, and a second man, who was not identified under privacy laws, remained hospitalized on Wednesday.
The gunman then poured gasoline around the back door of the hall and set a fire as he fled.
Two police officers passing by the hall on an unrelated call arrested the man, who was wearing a blue bath robe, a balaclava and what appeared to be black underwear. As he was put into a police cruiser, he muttered a French expression that can be translated as, "The English are awakening" or "The English are rising up."
The police said they would not release the name of the suspect, who was taken to a hospital after complaining of an undisclosed illness, until he appeared before a judge, which was expected Thursday.
Several news outlets in Quebec, however, identified him as Richard H. Bain, the owner of an outdoor outfitting business near the popular Mont Tremblant resort. He will turn 62 on Saturday, the police said.
A motive was unclear. Officials in Mr. Bain's hometown, La Conception, said that while he sometimes complained about the local government bureaucracy, he did speak French, if imperfectly, and never complained to them about provincial laws mandating the use of the language in many commercial settings.
Expanding those language laws to include small businesses was among Ms. Marois's prominent campaign pledges. But the fact that the Parti Québécois did not capture a majority of legislative seats makes realizing that pledge difficult and is likely to thwart any significant actions by her government to secede from the rest of Canada.
Neither of the two major opposition parties, particularly the Liberals, who have been in power for nine years and who oppose separation, is likely to vote with the Parti Québécois. (The Liberal leader, Jean Charest, who lost his seat in Tuesday's vote, said Wednesday that he would leave politics.)
"She's going to be very circumscribed," said Antonia Maioni, a professor of political science at McGill University in Montreal.
Pierre Martin, a political scientist at the Université de Montréal, said that Ms. Marois does have at least one way to maintain a high profile for separatism. She has already promised to demand that the federal government turn over its control of unemployment insurance and foreign aid to the province, which Professor Martin said would most likely be the first of many such demands.
"She has to make some kind of demonstration that Quebec can't advance in the straitjacket which she portrays federalism as being," he said.
That could make life difficult for Canada's prime minister, Stephen Harper, whose Conservative Party is unpopular in Quebec.
While Mr. Harper usually favors reducing the power of the central government, concessions for Quebec do not sit well with the Conservative Party's power base in Western Canada.
But flatly rejecting all of Ms. Marois's demands would only help cement her case against federalism.
"The challenge for Stephen Harper is to give some, concede some, but not look like he's pandering," Professor Martin said.
Mimi Wells contributed reporting.
Correction: September 5, 2012, Wednesday
This article has been revised to reflect the following correction: An earlier version of this article misidentified the suspect's hometown. It is La Conception, not Le Constant.
This article originally appeared in The New York Times.