Rosario, 30, arrived at the hospital late Tuesday in full
"He was resuscitated in the emergency room back to a stable heart rhythm and
Del Rosario trains at Team Oyama, a gym in Irvine. His trainer could not be reached for comment.
"We're hoping to learn more tonight," House told the Daily Pilot on Wednesday afternoon.
Del Rosario competes in the Ultimate Fighting Championship, which features mixed martial arts.