SEATTLE (Reuters) - A Seattle high school that shares a building with a children's museum in a popular tourist area was evacuated and a 16-year-old student arrested on Monday after he was discovered on campus with an explosive device, Seattle police said.

Police responded to the Center School, a small public school in the same building as the Seattle Children's Museum, after receiving a tip that a student had a Molotov cocktail, police said in a statement.

"The school was evacuated as a precaution," the statement said. It was not immediately clear why the student had brought the firebomb to school or what police did with the explosive. It was also not yet clear what charges the student might face.

The incident comes three days after a 15-year-old high school student in Marysville, Washington, north of Seattle, opened fire on classmates inside the school cafeteria, killing two girls and wounding three other students.

The shooter then turned the gun on himself, police said.

The Center School has a focus on the arts and community engagement, and its 300 students are drawn from across Seattle.

(Reporting by Victoria Cavaliere; Editing by Cynthia Johnston)