GANGTOK, India, June 9, 1997 (CNN) -- Heavy rains triggered landslides in mountainous northeastern India, killing at least 28 people, authorities said Monday.

At least nine landslides hit Gangtok, capital of the Himalayan state Sikkim, said police chief P.C. Sharma. One landslide swept a four-story building onto two government bungalows, crushing nine people, Sharma said.

Twenty-four bodies have been recovered and at least four more were presumed dead, the chief said. The death toll may rise, he said, as rescuers search the rubble.

"We are accustomed to landslides here and there," Sharma said, "but this time it's something very serious."

The monsoon season, later in the year, usually brings landslides to the state. Gangtok sits at an altitude of 5,000 feet (1,525 meters), surrounded by steep slopes rising to 8,000 feet (2,440 meters).

"I heard a loud noise around 9 last evening and rushed out along with my family members and took shelter on the road," survivor Shipintso Bhutia said of Sunday night's mudslide. "Seconds after, I saw the hillside tumbling down, which took away my house."

Sikkim, surrounded by Tibet, Nepal and Bhutan, has been part of India since 1975, when its legislature voted to abolish its monarchy and join the Indian union.