The gang’s not all here for a “Stranger Things” event in New York City … because David Harbour and Millie Bobby Brown are noticeably absent.

Most of the cast was at the “Stranger Things: The Final Season Celebration” at New York City’s Paley Center Thursday … but David and Millie were nowhere to be found.

As we reported … David was initially supposed to attend the event, but he was scrubbed as an attendee on the event website.

David’s absence comes on the heels of some bizarre behavior in Encinitas, CA. He’s had a tough year, going through a messy divorce with Lily Allen.

Millie wasn’t scheduled to attend either, and she didn’t make a surprise appearance.

There’s been a rumored feud between David and Millie, but we’ve seen them together at other “Stranger Things” events recently.

According to our law enforcement sources, the unidentified suspect was found with a self-inflicted gunshot wound at a storage facility in Salem.

As you know … two students were killed and nine people were injured during the shooting over the weekend at the Rhode Island campus — and police have been frantically searching for the shooter since.

They brought a person of interest into custody shortly after the shooting — a 24-year-old Wisconsin man who was later released.

New footage shows Nick Reiner walking around in Santa Monica hours before his parents’ dead bodies were discovered in their Brentwood home … and he’s heading toward the hotel he checked into.

TMZ obtained surveillance video from a local business on Santa Monica Pier. You see Nick walking down the sidewalk, towards the Pierside Santa Monica hotel.

The video was shot around 4 AM Sunday … and Nick looks like he’s carrying a black backpack and wearing a hat … just like the video we obtained of him at a Brentwood gas station earlier in the evening.

We don’t know if this video of Nick was shot before or after he allegedly murdered his parents.

What we do know is that he checked into the hotel approximately 6 minutes after he’s seen in this footage. Sources with direct knowledge told us no one saw any blood on Nick when he arrived at the hotel at 4:15 AM.

We broke the story … hotel staff found blood in the shower and on the bed in Nick’s room … and the window was covered by bed sheets.

Nick was arrested Sunday night near USC campus in downtown Los Angeles … and he’s since been charged with murdering his parents, Rob and Michele Reiner.

In footage from his arrest, Nick has a red backpack … so it looks like he switched bags at some point after going to the hotel.