PADANG, Indonesia — A powerful earthquake crumpled houses across a large swath of western Indonesia yesterday, killing at least 70 people and injuring hundreds, authorities said, predicting that the toll would rise.

The magnitude 6.3 quake struck on Sumatra Island and was felt as far away as neighboring Malaysia and Singapore, where some tall buildings were evacuated. It was followed by several strong aftershocks.

“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 who uses a single name. Along with thousands of others, he was running to higher ground, fearing a tsunami that never came.

Indonesia straddles one of the world’s most seismically violent zones and has been hit by a string of natural disasters in recent years, the most deadly being the 2004 tsunami that killed 160,000 people on Sumatra’s northern tip.

Indonesia’s Cabinet secretary, Sudi Silalahi, told reporters in Jakarta that at least 70 people had been killed by the quake, which hit the island’s western coast. The worst-affected area appeared to be Solok, a bustling town close to the epicenter where two children were killed by falling debris on a school playground.

Dozens of buildings had been destroyed and hundreds others damaged, a local police chief, Lieutenant Colonel Budi Sarwono, said. TV footage showed a flattened three-story home and thick cracks in the road.

Hospitals were overflowing with patients, many of them with broken bones and cuts. Scores were laid out on cots where they were given emergency care, said Mr. Sarwono.

“So far we have recovered 19 bodies and hundreds of injured people,” he said. “The two hospitals are overwhelmed with victims.”

At one hospital in nearby Padang, panicked doctors and nurses fled into the streets, startled patients limping behind, according to Metro TV.

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 20 miles below Solok. It was followed by several strong aftershocks, one measuring 6.0.

The tremor was felt in Singapore, 265 miles from the quake’s epicenter, forcing the evacuation of several older office buildings, TV station Channel NewsAsia reported.

In Malaysia’s southern coastal city of Johor, citizens fled offices, buildings, and shopping centers, eyewitnesses said.

Indonesia, the world’s largest archipelago, is prone to seismic upheaval because of its location on the so-called Pacific “Ring of Fire,” an arc of volcanos and fault lines encircling the Pacific Basin.

In addition to the 2004 tsunami, earthquake-spawned waves also killed nearly 5,000 on Java Island last year.

Yesterday’s quake was about 660 miles west of Jakarta.