JERUSALEM — An Israeli teenager was killed and her father and brother were wounded on Friday when a homemade bomb exploded near a natural spring in the occupied West Bank, one of many small oases where Palestinians and Israelis seek to cool off but that have become hot spots in the conflict.

Government officials declared it an act of terrorism, and security forces set up roadblocks near Ramallah to try to catch those responsible.

The attack at Ein Bubin, a spring in the wooded hills near the small settlement of Dolev, roughly midway between the cities of Ramallah and Modiin, killed the teenager, Rina Shnerb, 17, the authorities said. She had visited the spring with her father, Rabbi Eitan Shnerb, and an older brother, Dvir, 19. Both men suffered shrapnel injuries and were airlifted to Hadassah Medical Center in Jerusalem.

The rabbi’s brother, Shmulik Shnerb, spoke to reporters at the hospital, calling his niece, whose home was in the Israeli city of Lod, a “martyr,” saying, “May God avenge her death.”