SANTIAGO, Chile — Firebombs exploded before dawn on Friday at three churches in Santiago, Chile’s capital, an act of violence aimed at Pope Francis, who is to begin a weeklong visit to Chile and Peru on Monday. The police defused two other explosive devices that failed to detonate outside other churches later in the day.

No one was injured, and only minor physical damage was reported. President Michelle Bachelet appealed for calm, urging Chileans to welcome the first papal visit since John Paul II visited Chile in 1987. “I also want to invite you all to experience this visit in a climate of respect, solidarity and happiness,” Ms. Bachelet said in a statement.

No organization immediately claimed responsibility for the attacks, but pamphlets left at the sites of the first three bombings alluded to several issues, including the plight of the Mapuche, an indigenous people who have been battling loggers and farmers in the impoverished region of Araucanía in southern Chile.

Early on Wednesday, Pope Francis is to fly to Temuco, the capital of the Araucanía region, about 400 miles south of Santiago. The government has intensified security measures there, with more than 4,000 additional police officers and special forces troops, even though Francis is expected to stay only for a few hours.