Two strong earthquakes have hit Indonesia's Sumatra island , killing at least 70 people with dozensinjured. The tremors on Tuesday (March 6) were felt as far away as Malaysia and Singapore, where several buildings were evacuated. The first quake of magnitude 6.3 was felt in the West Sumatra provincial capital of Padang at around 11 a.m., sparking panic among seaside residents who feared it might trigger a tsunami. A second 6.0 magnitude earthquake struck the same area two hours later, causing more panic. However, there was no immediate tsunami warning after the quakes, which were on land. Indonesia's cabinet secretary Sudi Silalahi said 70 people had been killed. The United States Geological Survey said the first quake's epicentre was around 420 km (260 miles) from Singapore. The Indonesian national quake centre measured the quake at 5.8 on the Richter scale. Some buildings collapsed and several homes and other buildings were badly damaged by the tremors that sent several people scrambling for safety, including 200-300 patients who ran out of a hospital in Padang, a Reuters witness said. The mayor of Solok said hospitals were overwhelmed with dozens of injured. Padang is one of the few Indonesian cities where a tsunami warning system is in place. A quake in the Indian Ocean off Sumatra island in December 2004 and the tsunami it caused left about 170,000 people dead or missing in Indonesia's northern Aceh province. Earthquakes are frequent in Indonesia, the world's fourth most populous country. Its 17,000 islands sprawl along a belt of intense volcanic and seismic activity, part of what is called the "Pacific Ring of Fire". In March 2005, a powerful earthquake devastated Nias island, off the west coast of northern Sumatra, killing hundreds of people and leaving tens of thousands homeless. A Reuters witness said Padang residents tried to reach higher places and their vehicles crowded main streets, triggering congested traffic across the city. Callers told a Jakarta-based radio station that residents in several West Sumatra towns ran out of their houses when the quake was first felt. Tall buildings in Singapore's business district swayed slightly, occupants said, and the tremor was also felt in other parts of the island. Traders said there was little or no impact on financial markets trading. The tremor was also felt in west coast areas of Malaysia, the meteorological office in that country said.