meaning of the phrase "on it"

Hi everyone
Id like to ask what “on it” means in the following context:

The mayor, his aides and a reporter are in the car. Suddenly a siren peals through the air at defeaning levels. Then the author wrires as follows:

Putting her hands to her ears, she asked, “What the hell?–”
Nobody responded until the siren died down, at which point Liebniz said, “Ion storm. Mike?”
"On it," Mike said. He started steering the car into a U-turn, and headed for the nearest parking garage.

“On it!” is short for “I’m on it!” That means he’s aware of a problem and is already doing something to stop it or avoid it. In this case he’s saying it because he’s already aware of the ion storm and is going to get the car out of harm’s way.

A boss might say to an employee, “That empty office needs to be cleaned today,” and the worker might say, “I’m on it!” meaning, “Say no more! I’ll take care of it right away!”

Thank you very much, Jamie.