According to the LAPD, cops were called to a home the two were renting in the Hollywood Hills on Friday around 2:40 AM after a call came in reporting an alleged battery.
The fight was so bad, that Ronnie reportedly ran after Jen with a knife in hand while carrying their child.
FOX reporter, Gigi Graciette obtained a photo of Ron on a stretcher after he had been taken into custody.
Officials say the two stars were, "involved in some kind of physical altercation," and that when police arrived Ronnie was extremely, "uncooperative."
We're told a "minor" use of force was used on Ronnie in the form of a taser to get him under control before he was taken into custody and brought to the hospital.
He has not been officially booked yet, but once doctors clear Ronnie to leave the hospital he will be processed on charges of felony domestic violence.
Ronnie and Jen's 1-year-old daughter, Ariana, was also present and involved in the altercation, but police confirm she was not harmed in the melee.
We're told a protective order has also been issued for Jen and Ariana.
The arrest by the "Jersey Shore" star comes hours after they were spotted walking around L.A. and proclaiming their love for each other.
Jen was even showing off some new jewelry she got on Rodeo Dr. and gave a shoutout to Ronnie on "National Boyfriend Day."
The two have had an extremely volatile relationship with a history of domestic violence.
Earlier this year, Jen was arrested on an outstanding warrant for domestic violence after throwing an ashtray at Ronnie during a night out partying, but those charges were later dropped when the couple reconciled.