Lights flashing

[pablox]

Hello,

I noticed something odd in the parking lot. Someone was walking in front of me to their car that was 2 bays next to mine. When he pressed his key to unlock his car mine's lights started flashing and another car's next to mine as well. So that when he pressed his key, three cars started to flash in total.
What could this be? Has he activated an alarm somehow? His car didn't make any noise when he unlocked it.
If that helps, in the Audi, only the white lights were flashing. When I unlocked it myself it unlocked normally and the lights stopped flashing.

Thanks!