MATARAM, Indonesia: A powerful earthquake rocked Indonesia’s Lombok on Sunday, killing three people, sending resident running from their homes and triggering a tsunami alert, just a week after a quake killed 17 people on the holiday island.

The latest tremor had a magnitude of seven and struck just 10km underground according to the US Geological Survey.

It was followed by two light to moderate secondary quakes and nearly two dozen aftershocks.

There were reports of damage in Lombok and neighbouring islands.

Sutopo Purwo Nugroho, spokesman for Indonesia’s disaster mitigation agency, said many buildings were thought to have been affected in Lombok’s main city of Mataram.

“They are mostly buildings with weak construction material,” Nugroho said.

Residents in Mataram described a strong jolt that sent people scrambling out of buildings.

“Everyone immediately ran out of their homes, everyone is panicking,” Iman, who like many Indonesians has one name, told AFP.

The electricity was knocked out in several parts of the city and patients were evacuated from the main hospital, witnesses and officials said.

Pictures showed patients lying on their beds outside the clinic while doctors in blue scrubs attended to them.

Singapore’s Home Affairs Minister K. Shanmugam, who was in Lombok for a security conference when the earthquake struck, described on Facebook how his hotel room on the 10th floor shook violently.

“Walls cracked, it was quite impossible to stand up,” he said.

Officials issued a tsunami warning, which was later cancelled.

Seawater entered two villages as high as 10cm and 13cm, Dwikorita Karnawati, head of the agency for meteorology, climatology and geophysics, told local TV.

The quake caused light damage as far away as the Javanese city of Bandung, some 955km from Mataram, but was felt strongly on the neighbouring resort island of Bali.

People could be heard screaming as locals and tourists ran onto the road.

Agung Widodo, a resident of Bali’s main town of Denpasar, said he felt two strong tremors.

“The first one lasted quite a while, the second one was only about 2-5 seconds. The first one was the bigger one,” he told AFP.

Bali’s international airport suffered damage inside the terminal but the runway was unaffected and operations had returned to normal, disaster agency officials said.

Facilities at Lombok’s main airport were also unaffected, although passengers were briefly evacuated from the main terminal.

Early reports suggest the quake wrecked buildings in several districts across Bali.

The tremor came a week after a shallow 6.4-magnitude quake hit Lombok, killing 17 people and damaging hundreds of buildings.

It triggered landslides that briefly trapped trekkers on popular mountain hiking routes.

Indonesia, one of the most disaster-prone nations on earth, straddles the so-called Pacific “Ring of Fire”, where tectonic plates collide and many of the world’s volcanic eruptions and earthquakes occur.

In 2004 a tsunami triggered by a magnitude 9.3 undersea earthquake off the coast of Sumatra in western Indonesia killed 220,000 people in countries around the Indian Ocean, including 168,000 in Indonesia.