The number of dead was expected to rise as a result of the magnitude 6.3 quake on Sumatra island, which was followed by powerful aftershocks and was felt hundreds of kilometers (miles) away in Singapore, where some office buildings were evacuated, and in neighboring Malaysia.
"Women were crying out in terror. We all just fled as quickly as we could," said Alpion, a welder in the seaside town of Padang. Along with thousands of others, he was fleeing to higher ground, fearing a possible tsunami. Authorities said the quake did not cause any tidal activity.
Indonesian Cabinet Secretary Sudi Silalahi told reporters at least 70 people had been killed by the quake, the latest in a series of natural disasters to strike Indonesia in recent months.
The worst-hit area appeared to be in and around Solok, a bustling town close to the epicenter of the quake on Sumatra's western coast, which was spared destruction in the 2004 Asian tsunami disaster.
Two children and a teacher were killed in the town when a two-story building crashed onto a playground, said police spokesman Supriadi, who goes by only one name. Three family members were burned alive when their collapsed home burst into flames, town Mayor Samsu Rahim told a local radio station.
Hospitals in Solok were overflowing with patients, many of them with broken bones and cuts, Supriadi said. At least one hospital in nearby Padang which was spared serious damage was evacuated, sending panicked doctors and nurses fleeing with startled patients limping behind, according to Metro TV.
A witness in the town of Payahkumbuh said several two-story shops in the main street had collapsed and police and soldiers were digging for survivors, reports AP.
Local government spokesman Hasrul Piliang said the number of dead "would likely rise" because tolls from remote areas were still being collected and there were reports of others trapped under debris.
The U.S. Geological Survey said the tremor struck 33 kilometers (20 miles) below Solok. It was followed by several strong aftershocks.