SEATTLE - A minor earthquake with a magnitude of nearly 4.0 occurred at 5:09 a.m. Wednesday.

Earthquake experts at the U.S. Geological Survey reported receiving about 75 calls from startled residents in a wide area who said they heard a loud thump and felt what was described as a "sharp jolt."

"It was centered about six miles south of Oak Harbor, about 43 miles north-northwest from Seattle," said Randy Baldwin of the U.S.G.S. "There's a preliminary depth of 36 miles, so it's a fairly deep quake and the magnitude, the preliminary magnitude is of about a 3.7."  

The University of Washington seismology lab reports it was centered about two miles east-southeast of Coupeville.

A dispatcher in Oak Harbor for the Island County sheriff's office says it received several calls from people reporting they felt the quake.

Callers to Seattle TV and radio stations say they were awakened by shaking that rattled windows and pictures on the walls. One man, who says he felt the quake while sitting in a chair, says his cat gave him a funny look and ran down the hall.

Mitzy Cameron, who llives on the north end of Camano Island, told KING5 News that the quake shook her out of bed.

"That could be, depending upon how close in proximity they're located," said Baldwin.

Baldwin says there may be aftershocks felt in the area. "That's always to be expected. Generally they can last for several days after a quake."

So far, there are no reports of damage or injuries.

The Associated Press contributed to this report.