Police investigate a house on Esterlawn Private, a street in the Carlingwood area of Ottawa. The RCMP say they have made two arrests related to 'terrorist offences.' (Lorian Belanger/CBC)

The RCMP say they have arrested two Ottawa residents and expect to make more arrests for what they describe as "terrorist offences."

The RCMP's national security enforcement team arrested the pair early Wednesday morning, and search warrants are being executed, the Mounties said in a news release.

No charges have yet been laid.

Police sources told the CBC that two men were arrested at separate locations.

There were two raids, one at a residence at 91 Esterlawn Private near the intersection of Carling and Woodroffe avenues in the Carlingwood area, and a second at a highrise on Woodridge Crescent southwest of Esterlawn Private.

The two people were arrested in connection with plans that were in the developing stages and had yet to be executed, police sources told the CBC.

No further details were provided. Charges are expected to be announced at a news conference scheduled for Thursday afternoon, police sources said.

Neighbours said a quiet couple of Middle Eastern descent lived in the Esterlawn townhouse with a small child or possibly two children, the CBC's Simon Gardner reported.

Police arrived at the home at about 6:45 a.m. A neighbour said policewomen took the child or children during the raid, as two fully veiled women watched.

A spokesman for Public Safety Minister Vic Toews wouldn't comment on the investigation but issued a statement saying Canada remains "vigilant in protecting against threats."

"As Minister Toews has said, it is clear that Canada is not immune from international or homegrown radicalization," spokesman Chris McCluskey said.

The Muslim Canadian Congress issued a statement commending the RCMP for arresting the suspects before they could carry out their plan, and hoped the accused would be tried with due process.

With files from the CBC's Alison Crawford