During the whole New York truck attack, this was happening in California:

http://losangeles.cbslocal.com/2017/...entary-school/

RIVERSIDE (CBSLA/AP) — Police responded Tuesday to a barricade situation at a Riverside elementary school involving a parent, authorities said.
Castle View Elementary School in Riverside was evacuated shortly after 11 a.m. after a male parent was barricaded inside a classroom with another parent, according to police.
It’s unknown if the man is armed.
Riverside police Officer Ryan Railsback said he believes a male parent was holding a teacher or other school staffer hostage. He says it’s not known if the parent has a weapon.
The school was evacuated and the area where the barricade was occurring has been isolated.
Railsback says officers had been first called to the school for a disturbance and when they arrived, they found the parent barricaded inside a classroom.
Riverside Unified School District released a statement calling the incident “a disturbance inside of a classroom.”