NAMANGOFULO, Kenya — The military sealed off a region of western Kenya where land disputes have flared into violence, and witnesses said helicopter gunships were strafing the area yesterday to try to drive gunmen from forests and caves. “Always in this country, people are fighting over land,” the head nurse at Kitale District Hospital, Lucy Okello, said. Four girls were being treated there for severe burns after their village was attacked, allegedly by the Sabaot Land Defense Force, a militia fighting for the redistribution of land. The oldest girl, 15-year-old Joanne Temuko, wailed and held her head in her hands as nurses applied balm to her scorched back. Thirteen other civilians were hacked, shot, or burned to death in the attack last week. There was no claim of responsibility. A militia member said at the time that his group was simply trying to “correct historical injustices.”