Tommy Lee 'Knocked Out Cold' in Alleged Altercation with Son Stemming from Rocker's Tweets About Ex Pam Anderson

The alleged physical altercation that took place between Tommy Lee and his 21-year-old son Brandon on Monday stemmed from the rocker’s controversial tweets about his former wife — and Brandon’s mother — Pamela Anderson, PEOPLE confirms.

Los Angeles County Sheriff Department officers responded to an incident at Lee’s home in Calabasas, California, on Monday night, an apparent scuffle between father and son that left the Mötley Crüe drummer, 55, with a bloody lip. He was transported to a local hospital later that night.

Brandon, who was not at the scene when authorities arrived, has been named a person of interest in the ongoing investigation for criminal battery. So far no arrest has been made, and authorities say his attorneys are cooperating fully.

RELATED: Tommy Lee Claims Son Brandon, 21, Assaulted Him: ‘My Heart Is Broken’

An LASD official tells PEOPLE that in the lead-up to the alleged tussle, the pair had been arguing about a series of tweets Lee had posted responding to Anderson’s interview on Piers Morgan’s Life Stories that aired Saturday night on ITV. During the broadcast, the former Baywatch star, 50, discussed physical abuse she claimed to have endured from Lee during their relationship.

In 1998 Lee was sentenced to six months in the Los Angeles County Jail for spousal battery following an assault that left Anderson with bruises and a torn fingernail. She was reportedly holding their infant son, Dylan (now 20) at the time. Lee pled no contest to the charges.

“Think she’d find something new to discuss instead of rehashing old s— but I guess she has nothing else going on & needs attention Signed, ‘The abuser’ (who she texts every day & asks for me back),” he tweeted, referring to Anderson.

On Tuesday, Lee posted a (since deleted) photo of his swollen lip to Twitter. “My heart is broken,” he captioned the image. “You can give your kids everything they could ever want in their entire lives and they can still turn against you. Good job Brandon. Great son!”

A family source close to Brandon says was reportedly “defending himself” from his father who was allegedly intoxicated, according to TMZ.

Lee, however, shared his own version of events on social media. “My fiancée and I were in bed when my son busted into the room and assaulted me. I asked him to leave the house and he knocked me unconscious. He ran away from the police. THAT’S the truth,” Lee tweeted on Tuesday. (Lee and fiancée Brittany Furlan announced their engagement on Valentine’s Day.)

In the 911 call, obtained and released by The Blast, Furlan says, “My stepson and my fiancé got into a fight … [Lee] didn’t hit his son, his son pushed him. Then [Lee] asked him to leave and was like, ‘Here’s the door’ and put his arm on his son’s shoulder. His son punched him in the face and knocked him out cold. He’s bleeding … He punched him really hard in the face and he went flying backwards. He’s totally out. Like a light.”

She continued, “My stepson has guns in his room and that’s why I’m freaked out; I just locked the door.” When asked what the fight was about, Furlan says, “[Brandon’s] mom — [Lee] got mad and posted some ugly photos of her.” She later tweeted, “Violence is NEVER the answer.”

Meanwhile, on Monday, Brandon spoke out on Instagram Story, saying, “As I get older, I have started to realize that there are very few people you can trust … that’s my super depressing thought for tonight. Just thought I’d share it and be a d—.”

Brandon and representatives for Lee and Anderson did not immediately respond to PEOPLE’s request for comment.