HELENA, Mont. (AP) - An earthquake with a preliminary magnitude of 4.6 shook southwestern Montana Tuesday morning, according to the U.S. Geological Survey.

The quake, reported at 9:46 a.m., was centered 28 miles northeast of Dillon. Reports to the USGS Web site said it was felt in Helena and Butte, as far away as Missoula and in North Fork, Salmon and in Elk City, Idaho.

"This is on the lower end," said John Bellini, with the USGS National Earthquake Information Center in Golden, Colo. "The kinds of things we'd see is cracked plaster, maybe cracked windows or on an old house with a chimney with poor brick it might cause some damage to that."

No damage was immediately reported in Beaverhead County, a sheriff's dispatcher said.