02:27 - Source: CNN
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Story highlights

Three of the people die of heat attacks, officials say

An 8.6-magnitude quake struck Wednesday

It was followed by an 8.2-magnitude aftershock

There were no immediate reports of major damage

Jakarta, Indonesia CNN  — 

A massive earthquake struck off the coast of the Indonesian island of Sumatra on Wednesday afternoon, triggering a tsunami watch for the Indian Ocean, which was later canceled.

Three of the people died from heart attacks while the others died of shock after two earthquakes struck Wednesday, officials with Indonesia’s Disaster Mitigation Agency said.

The first massive earthquake struck off the coast of the Indonesian island of Sumatra on Wednesday afternoon, triggering a tsunami watch for the Indian Ocean, which was later canceled. It was an 8.6-magnitude quake.

The second large quake, with a magnitude of 8.2, occurred off the west coast of Sumatra about two hours later, the U.S. Geological Survey said.

Gary Gibson from the Seismology Research Center in Melbourne, Australia, said the location of the second quake reduced the possibility of a tsunami.

In Thailand, the National Disaster Warning Center issued an evacuation order for residents and tourists along the Andaman coast, state-run news agency MCOT said.

CNN’s Jethro Mullen, Josh Levs, Kathy Quiano, Harmeet Shah Singh, Mari Ramos and Sean Morris contributed to this report.