Parts of the Peruvian capital were blacked out tonight, and officials blamed a guerrilla force that they said also caused a momentary blackout of runway lights as Pope John Paul II arrived from a trip to the north.

The runway lights went out at 8:45 p.m. (7:45 p.m. EST), but a control-tower official said power was restored almost immediately by the automatic generating system, The Associated Press reported. The pope's twin-engined jet, arriving from the northern coastal cities of Piura and Trujillo, landed safely.

At 9:15, much of Lima went dark. Then, two huge hammer-and-sickle symbols of the Maoist Shining Path movement lit up on mountainsides visible from the city.

Witnesses reported three explosions in two districts of the city, including the affluent suburban neighborhood of Monterico.

With television blacked out, the state-owned radio, operating with an emergency generator, reported that electricity returned to some parts of the city at 9:45 p.m. But the city center remained dark.

The pope was driven to the papal nuncio's residence, as scheduled, where authorities had installed a special power generator, the radio reported. It said a large crowd gathered in the darkened street and the pope appeared on a balcony to acknowledge their cheers.

The Shining Path insurgents have claimed responsibility for bombs that have blacked out all or parts of Lima more than half a dozen times in the past two years. Yesterday, John Paul traveled to Ayacucho, a focal point of fighting between the guerrillas and government forces, and appealed to the rebels to give up violence.

Peruvian authorities had been concerned about possible terrorist attacks by the leftists during the pope's five-day visit, and more than 14,000 men were assigned to provide security in Lima alone. Until tonight, authorities had reported no attempt to disrupt the pope's activities.

The blackout came at the end of the day in which the pope continued a rhetorical offensive against radical practices in the Latin American church.

The pope hammered home his conservative interpretation of liberation theology, the doctrine of social activism that has had strong influence on the Peruvian clergy. "Evangelists have the undeniable duty of a strict and loving loyalty to the teachings of Jesus," John Paul said in a homily at Piura's airport. "Because evangelists are not owners of the word of God, but its ministers and its servants."

John Paul strongly attacked "alterations of the Gospel and true evangelism, falsehoods and false prophets, the rereadings of the Gospel . . . inspired by fashion or sociopolitical visions."

The pope's attack appeared directed both at radicals within the Roman Catholic Church and non-Catholic evangelistic groups that have won a growing following in some parts of Latin America.

The pope was enthusiastically cheered by large crowds in the searing heat of Trujillo and Piura as well as in grittily urban Callao. Officials in Trujillo reported that the pope drew an audience of close to 1 million, the third time in his four days in Peru that gatherings of 1 million or more have been reported.