NEW DELHI, India (AP) _ A severe earthquake struck a seismic hot zone in India's Himalayan foothills today, toppling houses, causing landslides and killing at least 73 people, officials said.

It was the strongest earthquake this century in the quake-prone mountains, with a magnitude of 6.8 and lasting nearly 40 seconds, India's seismological department said, according to the Press Trust of India news agency.

The epicenter was in a remote area of the Kumaon hills in the state of Uttar Pradesh, 185 miles northeast of New Delhi near India's border with China.

Police said scores were injured and the number of victims was likely to rise. Reports of casualties and damage were sketchy long after the quake, which jolted northern India just after midnight local time (2:05 p.m. EST Sunday).

Telephone lines to the area were knocked out. Many of the villages in the region have no communications at all and can be reached only by dirt paths.

A 10-mile stretch of road leading to Chamoli, the town nearest the epicenter, was blocked by landslides. Some 600 road workers were rushed to the area to begin clearing the debris.

``It looks like half the mountain had come off,'' said district magistrate Uma Kant Pawar, Chamoli's top appointed official.

``We were watching a Hindi movie on television when chairs, wardrobes and beds started toppling over,'' he said, reached by telephone. ``Before we could realize what was happening, the electricity went off and the whole area plunged into darkness.''

Pawar said he heard a deafening rumble of rocks and earth crashing down the nearby mountain slope.

A column of army soldiers and 20 medical teams left for the area to help the victims, but it was not clear if they could get through, B.M. Vohra, commissioner of the Dehra Dun district, told The Associated Press.

Three army and state government helicopters flew into the district shortly after sunrise to survey damaged villages, evacuating the most seriously injured to the city of Dehra Dun.

The area is known as a seismic danger zone. The Himalayas, one of earth's youngest mountain ranges, are still growing and unstable. Eight tremors have been recorded this century measuring more than magnitude 6. One quake in 1991, measuring 6.1, killed more than 1,000 people near the town of Uttarkashi.

Last year, the same area was shaken by dozens of landslides, including one that wiped out a camp of Hindu pilgrims. More than 200 people were killed.

Pawar said 41 bodies were recovered from Chamoli, a town of simple stone and mud buildings that were mostly destroyed or badly damaged. Altogether, 58 people in Chamoli and 15 in nearby Rudraprayag were killed, officials said. Among Chamoli's victims were five prisoners in the district jail which collapsed.

The quake also rocked the other side of the Chinese border, but there were no immediate reports of casualties, said the Xinhua news agency. A series of aftershocks followed the temblor.

India's most lethal earthquake in recent times killed nearly 10,000 people in western India in 1993. The most powerful quake was in 1950 in Assam in eastern India, measuring 8.5.