JAKARTA: A powerful earthquake rocked western Indonesia Wednesday, trapping thousands under collapsed buildings — including two hospitals — and triggering landslides. At least 75 people were killed on Sumatra island and the death toll was expected to climb sharply.

The magnitude 7.6 quake struck at 5:15 p.m. local time (1015GMT, 6:15 a.m. EDT), just off the coast of Padang city the U.S. Geological Survey said. It was along the same fault line that spawned the massive 2004 Asian tsunami that killed more than 230,000 people in a dozen countries.

A tsunami warning for countries along the Indian Ocean was issued, and panicked residents fled to higher ground fearing giant waves. The warning was lifted about an hour later.

When the quake struck, the ground was shaking so hard that people sat down on the streets to avoid falling over, footage shot in Padang and broadcast by local TVOne network showed.

Children screamed as residents tried to put out fires started in the quake. Thousands fled the coast in cars and motorbikes, honking horns.

Initial reports received by the government said 75 people were killed, but the real number is "definitely higher than that," Vice President Jusuf Kalla told reporters in the capital, Jakarta.

"It's hard to tell because there is heavy rain and a blackout," he said.

Health Minister Siti Fadilah Supari told MetroTV that a mall and two hospitals had collapsed in Padang — a sprawling low-lying city in Western Sumatra province of around 900,000 people that geologists have warned could be vulnerable to a massive quake or tsunami.

"This is a high-scale disaster, more powerful than the earthquake in Yogyakarta in 2006 when more than 3,000 people died," Supari said, referring to a major city on the main island of Java.

Rustam Pakaya, head of the Health Ministry's crisis center, said "thousands of people are trapped under the collapsed houses."

A field hospital was being prepared to assist the injured and medical teams were on the way from neighboring provinces, he said.

"Many buildings are badly damaged, including hotels and mosques," said Wandono, an official at Meteorology and Geophysics Agency in Jakarta, citing reports from residents.

Footage from Padang showed flattened buildings, the foot of one person sticking out from beneath the debris.

"The earthquake was very strong," said Kasmiati, who lives on the coast near to the epicenter. "People ran to high ground. Houses and buildings were badly damaged."

"I was outside, so I am safe, but my children at home were injured," she said before her cell phone went dead.

TV One said the quake triggered landslides that cut all roads to Padang. Power and telecommunications were also cut. Fire also broke out in buildings on a road to the city, officials said.

"I want to know what happened to my sister and her husband," said Fitra Jaya, who owns a house in downtown Padang and was in Jakarta when the quake struck. "I tried to call my family there, but I could not reach anyone at all."

Wednesday's quake came a day after a quake with a magnitude of between 8.0 and 8.3 in the South Pacific hurled a massive tsunami at the shores of Samoa and American Samoa, flattening villages and leaving at least 99 dead and dozens missing.

The epicenter of Wednesday's temblor off Indonesia lies several thousand miles (kilometers) to the west, on the other side of Australia.

The shaking could be felt in high buildings in Jakarta, several hundred miles (kilometers) away. It was also felt in neighboring Singapore and Malaysia.

Padang was badly hit by an 8.4 magnitude quake in September 2007, when dozens of people died and several large buildings collapsed.