A moderate earthquake shook Ottawa and Montreal on Wednesday, forcing office workers out onto downtown streets in Canada's capital.?

The US Geological Survey reported the temblor of magnitude 5.0 hit the Ontario-Quebec border area at 1741 GMT, rattling downtown Ottawa shortly after midday.

The USGS, which originally reported the quake at magnitude 5.5 before downgrading it, said the epicenter was 53 kilometers (33 miles) north of Ottawa.

It also shook Canada's most populous city Toronto, where global leaders are to gather this weekend for a G20 summit of the world's top developed and developing economies.

The earthquake was also felt as far away as New York and the American midwest state of Ohio.

Journalists in Canada witnessed walls in downtown office buildings shaking for several seconds. Cracks appeared in the Parliamentary Press Gallery building in Ottawa, and outside some people appeared shaken up, but unhurt.

The quake interrupted a press conference at the press gallery by an opposition MP who was shown in television broadcasts calmly gathering his notes before exiting, as journalists scrambled for the door to report on what was happening.

"It felt like someone set off dynamite below us," Genevieve Blais, who lives on Hawk Lake, near the quake epicentre, told public broadcaster CBC. "Pictures fell from the walls and lamps got knocked off their pedestals."

Most downtown Ottawa buildings, including parliament, appeared to have been evacuated as alarms rang out and firetrucks roared into the area.

Workers were allowed back into their offices after safety officials checked the integrity of buildings. Many public servants were also sent home early in the afternoon.

Local media reported minor damage to some homes and buildings. Windows at Ottawa City Hall shattered, according to CBC.

Canadian police said there were no injuries from the quake.

James Bowden, a former resident of Alaska who previously experienced several earthquakes in the northern US state, was standing in line at a fast-food restaurant on Ottawa's Sparks Street when he said he "heard the earthquake coming a few seconds before it hit."

"It sounded like a freight train barreling towards us," he said.

An avid reader of earthquake sciences, Bowden said Ottawa experiences earthquakes about every four or five years. "This one was fairly big," he said.

Several hundred much weaker earthquakes tied to the Logan faultline along the Saint Lawrence seaway strike in Quebec province each year.

The last major quake, of magnitude 6.0, struck in 1988 in the Saguenay region, about 500 kilometers north of Montreal.