The man said he was with one of the children and the assistant allowed him on as the bus drove toward the school.
The man got off the bus and a child then found the magazine and told the driver.
The man was taken into custody a short time later.
Police in Phoenix discovered the man had approached a boy near the bus stop but the young man walked away.
A parent in the Alhambra Elementary School District told KSAZ-TV she was “flabbergasted.”
Arrested was 29-year-old Jeremy West after media broadcasts of his description began to circulate leading to a tip.
West has been charged with endangerment, having a weapon on a school property, and criminal trespass.
More from KSAZ-TV.