JAKARTA A 7.8 earthquake shook Indonesias northwest island of Sumatra early Wednesday, prompting a tsunami warning and sending residents rushing for higher ground. There were no immediate reports of widespread damage.

The quake struck at 515 am local time and was centered 125 miles northwest of Sibolga in Sumatra at a depth of 28.6 miles, the US Geological Survey said.

The Indonesia Meteorology and Geophysics Agency issued a tsunami warning following the quake, but lifted it two hours later. The Pacific Tsunami Warning Center in Honolulu also issued a tsunami watch.

The center said no tsunami threat existed for other coastal areas in the Indian Ocean, although some areas could experience small sea level changes and strong or unusual coastal currents.

Fauzi, an official at the meteorology agencys Jakarta office who uses a single name, said there were no immediate reports of damage or casualties but officials were monitoring the situation.

Local media reports said the quake, which struck as people in the region were preparing for morning prayers, caused panic in North Sumatras capital of Medan and other cities in the province. Electricity was cut in Medan.

People in some cities along the southeastern coast of Sumatra as well as Sinabang on Simeulue island and Gunung Sitoli on nearby Nias island poured into the streets and rushed to higher ground, reports said. —AP