Two Raiders fans were arrested after an assault on a Ravens fan at Sunday's game in Baltimore, police told the Baltimore Sun.

Joseph Bauer, 55, was identified by his sister as the man who was assaulted, and now is in critical condition. He was taken to the University of Maryland Shock Trauma Center for a head injury, which his sister claims is a subdural hematoma. Doctors told her he has a 30 percent chance of survival.

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What's not clear is how the altercation started. Bauer's sister told the Sun her brother was involved in a verbal argument with Raiders fans when he was struck, and his head hit the concrete. The Ravens issued a statement Monday, saying the team is "deeply concerned about this assault."

Statement from the Baltimore Ravens regarding yesterday’s serious incident: pic.twitter.com/EHl3QtnZq9 — Baltimore Ravens (@Ravens) October 3, 2016

Scott Smith, 28, of Mount Vernon, N.Y., and Andrew Nappi, 31, of Eastchester, N.Y., were charged with first- and second-degree assault, the Sun reported.