Katmandu, Nepal ? Communist rebels killed at least 129 police, soldiers and civilians in unprecedented attacks Sunday in northwestern Nepal, undermining prospects for peace in this poor Himalayan kingdom still recovering from the shock of a massacre at the royal palace last year.

The attacks on government offices and an airport were the deadliest since the rebels began fighting to topple the constitutional monarchy in 1996 from remote mountain areas in this land of exquisite beauty but violent politics.

The rebels, who draw their inspiration from Chinese revolutionary leader Mao Tse-tung, had abandoned peace talks and ended a cease-fire in November, saying negotiations had produced no results. The government declared a state of emergency three days later.

Early Sunday, the rebels set fire to buildings and fired at police in the town of Mangalsen, the administrative center of the Achham district, killing 49 police officers, the Interior Security Ministry said in a statement. Mangalsen is about 375 miles northwest of the capital, Katmandu.

The guerrillas then attacked a small airport in the nearby town of Sanphebaga, killing another 27 policemen standing guard, a Home Ministry official said on condition of anonymity.

Forty-eight Royal Nepalese Army soldiers stationed in Mangalsen were also killed, Defense Ministry spokesman Bhola Silwal said in a separate news release.

Others killed in the attacks included the district’s chief administrator, Mohan Singh Khadka, a central intelligence bureau official and his wife, a postal worker and a civilian.

The rebels  a 3,000- to 4,000-strong force accustomed to using knives and aging muskets  on Sunday used modern weapons looted from the military during a previous attack.

The area was far away from Mount Everest region popular with tourists.

Earlier this month, the U.S. State Department issued an advisory to warn Americans about travel in Nepal. The guerrillas had recently attacked Lukla, the main entry point for the Mount Everest trek, and other popular tourist destinations in the Solu Khumbu Valley, the advisory said.