Screams erupted at a nearby hotel, where Microsoft founder Bill Gates was addressing an education and technology conference. He was whisked away as his audience bolted for the exits. Some audience members were knocked down by others trying to get out.
Video of the speech showed the stage shaking violently, and some overhead lights falling to the floor.
"This is the biggest thing I've ever felt," said Darcy Nebergall, 24, of Seattle, who was at work in a downtown skyscraper. "It felt kind of like a big rollercoaster going by. You could feel the building sway, but you know they're built to withstand this kind of stuff. Or you hope anyway."
Windows were popped out of some downtown building, and people who had left buildings gathered in the streets.
Alice Ayers, at her Seattle home, said it was "like a giant truck was going by. Everything was kind of bouncing."
Quake jolts lawmakers Closer to the epicenter in Olympia, legislators, government workers and visiting school children flooded out of the Capitol and other buildings. The state Senate was in session.
"The chandelier started going and the floor started shaking. Someone yelled get under the table and so we did," said Sen. Bob Morton, R-Orient. "The sudden violence let us know that this was a bad one."
Cracked plaster, gilt and even paintings fell from the walls, but Morton said he saw no sign of major structural damage.
Officials were particularly afraid the Capitol dome would collapse, he said. Some people linked hands as they walked down the marble stairs under the heavy dome.
"If that rascal had tumbled down, it would have been all over," Morton said.
Temblor felt in Portland In downtown Portland, office buildings swayed for 20 to 30 seconds, and local television stations were deluged by calls from viewers reporting rolling motion across the area.
Michelle Noonan of suburban Lake Oswego, Ore., said the quake was strong enough to move things around in her house.
"Everything was shaking," Noonan said. "It knocked over a wood pile outside house. Books fell off the shelf."
The quake was the largest to hit the Northwest since a 5.6 temblor centered in Scotts Mills, about 35 miles south of Portland, on March 25, 1993. That quake was the most destructive earthquake in Oregon's history, causing $30 million in damage.