JAKARTA, Indonesia (CNN)
-- A strong earthquake measuring 7.9 in magnitude struck Wednesday near southern Indonesia, the U.S. Geological Survey said.
A tsunami watch was immediately issued for the area.
The earthquake struck at 1810 local time (1110 GMT) Bengkulu province.
Several skyscrapers in Jakarta were rocked by the quake, which came at the end of the work day, said Andy Saputra, CNN producer in Jakarta.
"It's pretty strong and people are being evacuated from the tall buildings," he said.
The Financial Times' John Aglionby, speaking from Jakarta, told CNN: "The windows started shaking, the chairs started shaking - everything was shaking. We were up on the 16th floor of the building and decided we had to get out.
"It was a very bizarre experience. Some people were getting scared."
Jakarta is 605 km (375 miles) southeast of the epicenter. The epicenter believed to be Bengkulu Province in southern Sumatra.
Although some employees were too afraid to leave their offices, companies ordered immediate emergency evacuations, he said.
Workers exited structures via fire stairs and went into the street, away from buildings and other potential dangers, Saputra added.
High-rise buildings also were evacuated in Singapore, CNN Producer Martin Bohley said.
He said he felt shaking for almost a minute. "At first I wasn't quite sure, then I reconfirmed with staff at the hotel, then I turned on local media here, and local media had reported that several high-rise locations had felt it so strong that they had evacuated."
Ken Navidad at the USGS in Denver said the tsunami centers in the Pacific and Alaska initially said two quakes, but he did not know why. He said his agency has measured only one.
Tsunami warning centers in Hawaii and Alaska said no tsunamis were expected in their areas.
Indonesia, which sits on the Pacific Basin's "Ring of Fire" - an arc of volcanos and fault lines, is prone to seismic upheaval.
In December 2004, a massive earthquake off Sumatra island triggered a tsunami that killed more than 230,000 people, including 160,000 people in Indonesia's province of Aceh.
2004 ALL OVER AGAIN