Rescue workers are battling damaged roads and landslides to reach areas struck by Sunday's Himalayan earthquake that killed at least 100 people.

The 6.9-magnitude quake was centered in the Indian state of Sikkim and caused damage and fatalities across northeastern India, Nepal and the Chinese region of Tibet.

Authorities say the quake triggered a landslide at a hydroelectric power plant in the town of Saffo in north Sikkim state. At least 17 workers were killed, and many more remain missing.

Army officials say at least 45 tourists, including several foreigners, were rescued by helicopter Wednesday after being stranded in the popular mountain resort of Lachung.

Nepalese authorities reported at least seven quake-related deaths, while China's official Xinhua news agency said at least seven people were killed in southern Tibet.

Eighteen others were killed in the Indian states of West Bengal and Bihar.

Multiple landslides, fog and heavy rain had prevented many rescue workers from reaching the impact zone. Rescue efforts were in full effect Wednesday after more than 5,000 army troops blasted though rockfalls to clear a major highway leading to Mangan, a town near the epicenter.