A school near Rialto was placed on a lockdown Thursday, marking the third report of an armed person on a school campus in that area this week.
Both earlier incidents, at Rialto High School on Monday and Carter High School on Tuesday, were later determined to be false alarms.
The Thursday report concerned Joe Baca Middle School, 1640 S. Lilac Ave. in Bloomington, and streets near the school were closed as officers investigated…