Rescuers used heavy machinery to clear debris and search for survivors after a magnitude 6.9 earthquake killed at least 98 people on Indonesia's resort island of Lombok.
The island was further rattled by a magnitude 5.2 earthquake. Reuters witnesses said the quake woke up residents and tourists, who ran out of their hotels.
The National Disaster Mitigation Agency (BNPB) said it expected the death toll to rise once the rubble of more than 13,000 houses was cleared away after the second powerful quake in a week.
Power and communications were severed in some areas, with landslides and a collapsed bridge blocking access to areas around the epicenter in the north.
The military said it would send a ship with medical aid, supplies and logistics support.
Indonesia sits on the Pacific Ring of Fire and is regularly hit by earthquakes. In 2004, the Indian Ocean tsunami killed 226,000 people in 13 countries, including more than 120,000 in Indonesia.
Officials said more than 2000 people had been evacuated from the three Gili islands, where fears of another tsunami spread.
Michelle Thompson, an American holidaying on one of the Gilis, described a scramble to get on boats leaving for the main island during which her husband was injured.
"People were just throwing their suitcases on board and I had to struggle to get my husband on, because he was bleeding," she said.
BNPB spokesman Sutopo Purwo Nugroho said emergency units in its hospitals were overflowing and some patients were being treated in parking lots.
The main hospital in Tanjung was severely damaged, so staff set up about 30 beds in the shade of trees and in a tent on a field to tend to the injured.
A boy with a heavily bandaged leg wailed in pain, an elderly man wore a splint improvised from strips of cardboard on a broken arm, and some hurt by falling debris still had dried blood on their faces.
The Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) said more than 120 aftershocks were recorded after the quake.
Lombok had already been hit on 29 July by a 6.4 magnitude quake that killed 17 people and briefly stranded several hundred trekkers on the slopes of a volcano.
At magnitude 6.9, the latest big quake released more than five times the energy of the earlier one, the United States Geological Survey website said.
The tremor was powerful enough to be felt on the neighboring island of Bali where, BNPB said, two people died.
Despite it being a popular tourist destination, no foreigners were recorded among the dead, BNPB spokesman Mr Nugroho told a news conference. Some 236 people were injured and more than 20,000 displaced, he said.
"We have yet to ask for help from the international(community). But if there's any friendly country who wants to offer help, please do," Mr Nugroho said.
Oxfam said it was providing clean drinking water and tarpaulin shelter sheets to 5000 people and planned to intensify aid delivery.
The United Nations has offered to support rescue and relief efforts if required.
Sengiggi, a seaside tourist strip on Lombok, looked abandoned. Amid collapsed homes, most hotels seemed to have shut and beaches were deserted. The few restaurants left open were rationing food.
Long lines formed at the airport of Lombok's main town as foreign visitors cut their holidays short. BNPB said 18 extra flights had been added for leaving tourists.
"I was at the rooftop of my hotel and the building started swaying very hard ... I could not stand up," said Gino Poggiali, a 43-year-old Frenchman, who was with his wife and two children at the airport.
His wife Maude, 44, said the family was on Bali for the first quake and Lombok for the second.
"This is it for me in Indonesia. Next time we will stay in France, or somewhere close," she said.
Dutch tourist Marc Ganbuwalba injured his knee in a stampede of diners from a restaurant after the quake.
"We are cutting short our holiday because I can't walk and we're just not in the mood anymore," said the 26-year-old, sitting on a trolley at the airport with his leg bandaged.