The Indonesian island of Lombok has been hit by a strong natural disaster, as it still reels from the impact of Sunday's tremor. That number is expected to rise.
"We are still waiting for assessments from some of the more remote areas in the north of the island, but it is already clear that Sunday's quake was exceptionally destructive", Mr Rassi said.
Thursday's quake could be felt on Bali, another popular Indonesian resort island west of Lombok.
A witness told Reuters the aftershock sent people into the streets in panic and caused buildings to collapse.
Local authorities, worldwide relief groups and the central government have begun organising aid, but shattered roads have slowed efforts to reach survivors in the mountainous north of Lombok, which bore the brunt of the quake.
The national disaster agency said all those numbers were likely to increase, as more information comes in and more victims were found.
Tens of thousands of people have been left homeless following Sunday's shake.
"The quake does not have any tsunami potential", Hary Tirto Djatmiko, spokesman for Indonesia's meteorology, climatology and geophysics agency (BMKG), said of Thursday's aftershock.
The military said that five planes carrying food, medicine, blankets, field tents and water tankers left Jakarta for the island early on Wednesday.
Cleanup and rescue efforts are still continuing on the island, following the previous quakes.
The Indonesian Red Cross said it had set up 10 mobile clinics in the north of the island.
But some evacuees have complained of being ignored or experiencing long delays for supplies to arrive at shelters. "Where should we go if we have no house anymore, nowhere to live?" said the mother of 15- and 9-year-old girls.
With hospitals and clinics also affected, numerous injured have had to be treated in the open air or in makeshift clinics.
"We lack the infrastructure to perform operations because (they) need to be performed in a sterile place", Wibowo told AFP. "I do hope the government can help", she said.