Brazilian authorities say they've arrested a teenager allegedly involved in planning a school shooting in which eight people and two attackers died.

Sao Paulo's Court of Justice said Tuesday that the teenager has been sent to a jail for juvenile criminals for at least 45 days.

The teenager had been questioned last week and was initially allowed to return home. He hasn't been identified.

Police say the teenager is a former student of the Raul Brasil public school in the city of Suzano, on the outskirts of Brazil's largest city.

Attackers Guilherme Taucci Monteiro and Luiz Henrique de Castro killed themselves after killing seven people at the school and a used-car dealer elsewhere on March 13.

.