Two adults who’ve been linked to the Kansas City mass shooting are now facing murder charges and other serious counts … something just announced by KC prosecutors.

Lyndell Mays and Dominic Miller were both hit with 2nd-degree murder charges Tuesday … and they’re also up against armed criminal action and unlawful use of a weapon charges on top of that. These guys are different than the two teens who were charged last week.

It’s a stunning development, as we’re just now learning about the fact that cops even had these two men in their custody. Last we heard … they only had 3 people detained, including two juveniles.

Now, however … we know there are at least 4 people total at this point being implicated in this crime. Prosecutors say they’re not releasing mug shots yet ’cause these 2 men are still recovering in the hospital.

Prosecutors went on to say that there might be other people arrested and charged in the case — but for now, they’re starting here. They note that the 2 juveniles are being prosecuted by a different court … and their identities will not be released since they’re underage.

It’s unclear how old the two adult men are — and it’s also unclear when these two guys came onto the cops’ radar. But something interesting officials noted is that these two dueling factions — remember, they say this all started with an argument — did not know each other.

Prosecutors note evidence suggests this heated exchange led to a firearm being drawn by Mays … which then led to others pulling their firearms almost immediately afterward, including one by Miller. After the shots rang out — prosecutors say Miller’s weapon ended up being the one that hit Lisa Lopez-Galvan … although they’re pinning her murder on both guys.

360aproko broke the story … there were teenagers caught on camera on the scene Wednesday just before shots rang out — and eyewitnesses tell us they believe they were involved.

While our eyewitnesses say they never saw any of the teens open fire … they claim the person or persons they were facing off with, off-camera, did unload the first shots.

Kansas City officials say the investigation is still ongoing, and that they intend to hold everyone who participated in the tragedy responsible. At the moment, this is where they’re at.

In addition to Lisa’s death … at least 22 others suffered gunshot wounds that day.