The Quebec City mosque where six were killed and 19 injured Sunday evening has been the target of xenophobic messaging and vandalism in the past.

Last June, in the middle of the Muslim holy month of Ramadan, a gift-wrapped pig's head was left at the front door with a note saying, "bon appétit."

The consumption of pork is prohibited in the Muslim faith.

At the time, Mohamed Yangui, president of the Centre Culturel Islamique de Québec, said he believed the incident was isolated.

"We love everyone," Yangui said. "We have no problem with anyone and we respect people. We hope it's mutual. And we are always here to give the image of the good Muslim to all Quebecers."

The Centre Culturel Islamique de Québec is one of four mosques in the provincial capital.

Founded in 1985, the centre offers a Qur'an​ic school and courses in Arabic in addition to religious services.

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A few dozen people were inside the Islamic cultural centre of Quebec in the Sainte-Foy neighbourhood when the shooting began just after 8 p.m. (Canadian Press)

In November 2014, someone plastered the front door with posters that declared, "Islam hors de chez moi," or in English, "Islam out of my country."

The building, located in the city's Sainte-Foy neighbourhood, was bought in 2009.

Act of terrorism, Trudeau says

The attack on Sunday occurred during evening prayers. A suspect is in custody.

Both Premier Philippe Couillard and Prime Minister Justin Trudeau said the shooting should be treated as an act of terrorism. 

"It's a murderous act directed at a specific community," Couillard said.

The six victims range in age from 35 to 70, and some of the wounded are considered to be in critical condition.

Early Monday morning, the centre posted on its Facebook page: "All our thoughts for children to whom we must announce the deaths of their dads. May Allah lend them patience and endurance."