Two people have been arrested in British Columbia accused of plotting to plant a bomb outside the provincial legislature on Canada Day, police say.
John Stewart Nuttall and Amanda Marie Korody were self-radicalised and inspired by al-Qaeda, the Royal Canadian Mounted Police said.
The two Canadians from Surrey, British Columbia, were arrested on Monday, which was Canada's national day.
They are not believed to have been in contact with other militant groups.
"Our investigation demonstrated that this was a domestic threat, without international linkages," said Royal Canadian Mounted Police (RCMP) Assistant Commissioner James Malizia.
The pair were arrested in the town of Abbotsford and are in custody in Surrey, police said. They are due in court later on Tuesday.
'Committed to violence'
At a press briefing on Tuesday, RCMP officials said the pair had been charged with conspiring to place an explosive in a public place with the intent of causing death or serious injury and with possessing a device to cause an explosion.
They also face one count of knowingly facilitating a terrorist activity.
Authorities displayed images of pressure cookers, which they said were to be used to make bombs similar to those detonated at the Boston marathon bombing in April.
The RCMP said that inside the pressure cookers were nuts, bolts, nails, washers and other material that could kill or injure people.
The arrests are the result of a probe launched in February under an operation known as Project Souvenir, authorities said.
"The suspects were committed to acts of violence and discussed a wide variety of targets and techniques," said Assistant Commissioner Wayne Rideout.
He added that there had not been a threat to public safety and that authorities had intervened to make sure the devices were not dangerous.
"These devices were completely under our control, they were inert, and at no time represented a threat to public safety," the assistant commissioner added.