49ers' Bruce Miller -- Busted for Assault ... Allegedly Punched 70-year-old Man

2:29 PM PT -- Miller bonded out and has been released from custody.

12:12 PM PT -- The 49ers announced they've released Miller.

49ers fullback Bruce Miller was arrested for allegedly attacking 2 men -- including one who was 70.

TMZ Sports confirmed Miller was busted for aggravated assault, elder abuse, threats and battery. Bail's been set at $178k.

The altercation went down early Monday morning after Miller -- who cops say was drunk -- tried entering a room occupied by an elderly couple at Fisherman's Wharf Marriott Hotel.

When a neighboring guest, the couple's son, told Miller he was at the wrong room, the football player charged at him. That's when the 70-year-old father came to his defense and Miller punched him ... breaking several of the man's bones. Both men were taken to a hospital.

Miller fled but cops tracked him down across the street at another hotel where he was arrested. The 49ers released a statement, saying, "The San Francisco 49ers organization is aware of the media report regarding Bruce Miller. We are gathering the relevant facts of this matter and will continue to monitor the situation."