is shocked by Chris Brown's alleged assault of Rihanna
, West said Tuesday.
"I don't want to speak too much on it, but I was completely devastated by the concept of what I heard," West, 31, told Ryan Seacrest
on his KIIS FM radio show
"[Rihanna] has the potential to be, you know, the greatest artist of all time and, in that sense, I feel like [she is] my baby sis," added West. "I would do any and everything to help her in any situation."
West, who has previously toured with Rihanna, said he preferred not to get into specifics about whether he's spoken to her personally but labeled the situation "so devastating."
"I feel like, just as a person, I don't care how famous she is or even if she just worked at McDonald's, that should never happen. It should never come to that, to that place."
On Sunday, Brown, 19, was booked
on a felony criminal threat charge after he allegedly got into an altercation with Rihanna, 20.
"Chris knocked her around," a source close to the couple tells PEOPLE
. "Black eye, blood, bruises. She had to be treated by a doctor."
Los Angeles Police Chief William Bratton has said he expects the case will be handed over to the district attorney's office this week. Prosecutors could charge Brown with additional crimes.