Jakarta, Indonesia CNN —  

An operation is underway to evacuate thousands of tourists after a deadly earthquake that rocked some of Indonesia’s most idyllic islands late Sunday night.

At least 98 people, all Indonesian nationals, were killed when the 6.9 magnitude quake struck the popular tourist island of Lombok, Indonesian authorities said Monday. More than 200 were also injured.

The majority of those killed in the quake were hit by falling debris from collapsing buildings, said Sutopo Purwo Nugroho, the head of Indonesia’s disaster management department.

In total, an estimated 20,000 people have been displaced by the massive earthquake, Nugroho said.

Dramatic video tweeted by authorities showed hundreds of people, many believed to be foreign vacationers, crammed onto a beach on the island of Gili Trawangan as evacuation measures got underway.

Emergency personnel were racing to evacuate thousands of tourists from the three small Gili Islands as night began to fall. The islands, famous for their white sandy beaches and clear waters, are located near the epicenter of the quake on Lombok.

Hundreds of people try to leave Gili Trawangan, north of neighboring Lombok island.
HANDOUT/Indonesia Water Police/AFP/Getty Images
Hundreds of people try to le