Some Bronx police officers received thank you cards on Monday from a 7-year-old boy.

Zachary Becerra and his mother, Rosa Ortiz, delivered the cards to the 52 Precinct. The idea started last year when Zachary asked his mother about the murders of officers Wenjian Liu and Rafael Ramos in Brooklyn.

"I had to sit down and explain it to him, and he turned around and said he wanted to do something, so this is what we've been doing," says Ortiz.

The cards feature superheroes because Zachary says the officers are his heroes.

In return for the cards, officers gave Zachary an honorary 52 Precinct pin.

Zachary and his mother have already visited over 70 precincts. They plan on making their rounds until they've visited them all.