12:10 PM PT -- TMZ has learned the suspects got into the house through an unlocked window and A$AP's sister walked in on them.

A$AP Rocky's crib got rolled Tuesday night by armed robbers ... TMZ has learned.

The incident went down around 11:30 PM and, according to law enforcement sources, 3 male suspects knocked on the door to his L.A. home. When a woman answered, they pulled a gun and forced their way into the house.

We're told the men grabbed the woman and took her around the house while they scooped up a ton of loot -- about $1.5 million in jewelry and other property.

They also took a safe, but left it on the sidewalk for some reason before bolting in their getaway vehicle.

We're told the woman is a relative of A$AP, who was not home at the time. She was not tied up and it appears she was not injured.

Our sources say it looks like this was not a random hit, but rather the suspects targeted the rapper.

To that point ... late Tuesday, A$AP posted a video showing one of his buddies dropping a ton of cash into a bill counter.