JAKARTA, Indonesia (CNN) -- Rescuers on Monday searched through ruined buildings and landslides for survivors of a major earthquake that killed at least six people, injured more than 150 and caused significant damage on two remote islands in eastern Indonesia.

Police said three men and three women had been confirmed dead on the worst-hit island of Mangole. No deaths were reported on neighboring Taliabu island.

Police and local government officials said the death toll could rise since hundreds of people had been working in a timber factory on Mangole when the quake threw the equipment into the sea, killing five workers in that factory alone.

Officials also said they still did not have information of possible casualties or the level of destruction from outlying villages on Mangole island, which has a population of about 38,000.

A spokesman for the company operating the timber factory said a charter flight was due to arrive at Mangole on Tuesday to bring emergency supplies and evacuate victims.

Neither Mangole nor Taliabu has a major hospital, and local officials said seriously injured victims were flown to neighboring islands on emergency flights.

Officials have appealed for urgent food and medical aid, as many people lost everything they had after their houses slid into the sea.

Many roads have been cut and bridges destroyed, hampering relief efforts. Witnesses said large cracks scarred the streets of Mangole's largest town, Dofa, and elsewhere on the island.

More than 7,000 people spent Monday in tents or in the open for fear that their homes might collapse in the wake of the quake, which struck late Sunday.

Indonesian government seismologists measured at least 20 small-scale aftershocks following that tremor.

The Associated Press and Reuters contributed to this report.