ISTANBUL, Turkey (AP) _ A mild quake, registering a preliminary magnitude of 4, shook western Turkey on Thursday, sending thousands of people fleeing their homes and offices. No injuries or damage were reported.

The quake, centered in the town of Gonen in the western region of Balikesir, struck at midday, seismologists at the Istanbul Kandilli Observatory said.

Municipality officials in Gonen, a town of 35,0000, said residents rushed out of buildings in a panic.

Most of Turkey lies on the North Anatolian fault. Turkey was rocked by two massive quakes in 1999 that left some 18,000 people dead.