Bus No. 87 slid off a soft shoulder and into the ditch as it rounded a curve near SE 24th Way and 200th Avenue SE at about 6:45 a.m., authorities said.
A Washington State Patrol spokesperson said 17 students of all ages, from elementary school to high school, were aboard the bus at the time,
Another bus was dispatched to the scene to pick up the students and take them on to school, said "L" Michelle of the Issaquah School District.
Only one injury was reported - an elementary school student who sustained a sprained wrist. That student was picked up by his parents.
A State Patrol spokesperson said the bus driver was trying to be extra cautious when turning by giving as much space as possible to other vehicles, and in the process the bus' back tire caught on the edge of the ditch, causing the accident.
A tow truck has been sent to pull the bus from the ditch.