"There was some question as to whether it was a piece of space junk burning up, but it was not,'' said Geoff Chester, a spokesman for the Naval Observatory in Washington, D.C. "As far as I've been able to figure out, it was simply a rock falling out of the sky, as they are wont to do on occasion.''

Chester said it was a type of meteor called a bolide, one that appears like a fireball in the sky, and was about the size of a small piece of luggage or a computer monitor.

Nothing unusual was detected on National Weather Service radar, and authorities also ruled out aircraft problems or military flight tests.

Toby Smith, a University of Washington astronomy lecturer who specializes in meteorites, said the skybursts were reported over a wide area around 2:40 a.m.

Witnesses along a 60-mile swath of the Puget Sound region from the Tacoma area to Whidbey Island and as far as 260 miles to the east said the sky lit up brilliantly, and many reported booms as if from one or more explosions.

"It made a pretty big bang,'' said Petty Officer Andrew Davis at Whidbey Island Naval Air Station, 40 miles north of Seattle.