“So far we have received information of six deaths and 50-plus injured,” he said. “Most of the injured were allowed to go after preliminary treatment.”

Electricity and phone service in the city were largely unaffected, he said.

Jason Shimray, a relief and disaster management official in Manipur, said 155 buildings were known to have partially or fully collapsed.

Indian government seismologists reported that the epicenter of the quake was in the Tamenglong District, near the border with Myanmar.

Still, Mr. Shimray said the largest share of damage and casualties had occurred in Imphal.

Two teams of disaster response personnel, amounting to 90 people, were flown to Imphal on Monday morning, S. S. Guleria, a deputy inspector general of the National Disaster Response Force, said by phone in New Delhi. He said that an additional team was scheduled to leave for the city of Silchar in Assam later in the day and that several others were on standby.

Ms. Hazarika described the Tamenglong region as “very, very sparsely populated.”

The earthquake occurred shortly after 4:30 a.m., when most residents of India’s northeastern states were asleep, but people described buildings swaying and furniture toppling over because of repeated tremors in the space of a minute.

Officials in neighboring Bangladesh connected three deaths to the quake, including two men who had heart attacks and one who died escaping his home. Tremors were also felt in Bhutan and Myanmar.