Boise Police say they received a report about the man possibly being suicidal and were on their way to his house when they learned he had let the home and was on his way to Grace Jordan Elementary School.
Police say the man is reportedly a parent of a student at the school.
The school was placed on lockdown as a precaution.
Police say the man entered the school briefly, but quickly left and was met by officers in front of the school.
Officials say the man did not cooperate with the officers and had to be handcuffed and detained.
Police say the man is now in the custody of Idaho Health and Welfare.