UPDATE 7-Storm Fiona ravages Canada's east coast causing 'terrifying' destruction

(Adds details from PM Trudeau's press conference)

By Eric Martyn and John Morris

STEPHENVILLE, Newfoundland, Sept 24 (Reuters) - Powerful storm Fiona ripped into eastern Canada on Saturday with hurricane-force winds, forcing evacuations, knocking down trees and powerlines, and reducing many homes on the coast to "just a pile of rubble in the ocean."

The U.S. National Hurricane Center (NHC) said the center of the storm, downgraded to Post-Tropical Cyclone Fiona, was now in the Gulf of St. Lawrence and losing some steam. The NHC canceled hurricane and tropical storm warnings for the region.

Port aux Basques, on the southwest tip of Newfoundland with a population of 4,067, bore the brunt of the storm's rage.

The mayor was forced to declare a state of emergency and evacuated parts of the town that suffered flooding and road washouts.

Several homes and an apartment building were dragged out to sea, Rene Roy, editor-in-chief of Wreckhouse Weekly in Port aux Basques, told the Canadian Broadcasting Corp.

"This is hands down the most terrifying thing I've ever seen in my life," Roy said, describing many homes as "just a pile of rubble in the ocean right now."

"There is an apartment building that's literally gone. There are entire streets that are gone," he added. Police are investigating whether a woman had been swept to sea, CBC reported.

"We've gone through a very difficult morning," Button said in a Facebook video, adding that the evacuations had been completed. "We'll get through this. I promise you we will get through it."

Prime Minister Justin Trudeau met on Saturday morning with members of a government emergency response team, and later told reporters that the armed forces would be deployed to help with the clean up.

"We're seeing reports of significant damage in the region, and recovery is going to be a big effort," Trudeau said. "We will be there to support every step of the way."

Trudeau had delayed his planned Saturday departure for Japan to attend the funeral of former Prime Minister Shinzo Abe, but said he now would no longer make the trip. Instead he said he would visit the storm-damaged region as soon as possible.

Federal assistance has already been approved for Nova Scotia, Trudeau said, and more requests are expected.

Fiona, which nearly a week ago battered Puerto Rico and other parts of the Caribbean, killed at least eight and knocked out power for virtually all of Puerto Rico's 3.3 million people during a sweltering heat wave.