A strong earthquake jolted the Taiwanese capital, Taipei, early Friday, shaking buildings and waking residents.

The Central Weather Bureau said the 6.6 magnitude temblor struck at sea, 44 miles southeast of the eastern city of Ilan at 1:51 a.m. local time.

Ilan is about 50 miles east of Taipei.

There were no immediate reports of injuries or casualties, but the quake was felt for at least 30 seconds.

Earthquakes frequently rattle Taiwan, but most are minor and cause little or no damage.

However, a 7.6-magnitude earthquake in central Taiwan in September 1999 killed more than 2,300 people, and in December 2006 a 6.7-magnitude offshore tremor south of the city of Kaohsiung severed two undersea cables and disrupted telephone and Internet service to millions of users throughout Asia.