Hundreds of people are believed to have died in another earthquake in northern Indonesia, the same area where some 220,000 people lost their lives in December's tsunami disaster. Most of the latest confirmed dead were on the island of Nias, off the west coast of the island of Sumatra, where victims were trapped under collapsed buildings.

Three months after December's catastrophe, Indonesia is again coming to terms with a devastating earthquake that has left hundreds of people dead, and shattered island communities in the northwest of the country.

The huge eight-point-seven magnitude earthquake hit off the island of Sumatra at 11:10 Monday night, catching most people in bed. Residents of Banda Aceh, which suffered horribly in December, described their buildings shaking and floors bucking as they tried to get outside to safety.

The quake, close to the spot where a 9.0 magnitude tremor hit on December 26, triggered a region-wide tsunami alert. Authorities from Thailand to India, now on the watch for deep-sea earthquakes, quickly warned their people to move to higher ground.

Their fears were not realized. There was no tsunami this time, and the huge destruction wrought by the last disaster was avoided.

But for those living closest to the epicenter of the quake, the residents of the islands of Nias and Simeulue, that was little comfort.

Houses collapsed, trapping residents inside and killing hundreds.

The Indonesian government moved quickly to determine the scale of the disaster.

"A special mission is on the way by 9 a.m. this morning, to Nias, directly bringing doctors and medicines and stuff," said Andi Mallarangeng, the spokesman for Indonesian president, Susilo Bambang Yudhoyono. "Some of the relief sources we have in Aceh can be directly moved to Nias."

Mr. Yudhoyono himself postponed a trip to Australia scheduled for this week, and his aides said he would visit Nias within the next few days.

Aid agencies already in Aceh Province for reconstruction of December's damage refocused their resources to assist in the new emergency. But their efforts are being hampered by destroyed infrastructure: the airport in Nias is unusable, and many of the roads are impassable.

Relief work on the new earthquake is expected to delay the reconstruction effort in Aceh, but because the damage was fairly localized this time, aid officials say they believe they have the capacity to cope.