The San Juan County Sheriff's Office says one student and one adult at the Montezuma Creek school in southeastern Utah were airlifted, and 23 other students and adults were driven to hospitals.
Authorities didn't say which hospitals the students and staff went to, and details on their conditions were not immediately available.
The community of Montezuma Creek is on the Navajo Reservation, about 15 miles west of the Colorado border.
The Sheriff's Office and school superintendent say the leak appears to have been caused by a water heater with a blocked ventilation system. The school was evacuated and will remain closed Monday.
State enrollment data show about 200 students attend the school.