PORTLAND, Ore. (KOIN) — Hiteon Elementary School cancelled classes Thursday after a mysterious smell filled the halls, the Beaverton School District announced.

In a letter sent to parents, the district said the school would be closed due to an “unknown odor.”

School officials said parents shouldn’t send their children to the school. Students that caught a bus or walked to school will be waiting at the school’s playground and need to be picked as soon as possible.

KOIN 6 News will update this story when more information becomes available.