A bar fight between brothers in the west metro area last weekend has landed one in the hospital and the other in jail, authorities said.

Derrick D. Sommerfeld, 32, of Bloomington, sustained a severe head injury in connection with the attack about 11:20 p.m. outside the Riverside Bar in Watertown, the Carver County Sheriff's Office said. He remains in serious condition at Hennepin County Medical Center.

Under arrest on suspicion of first-degree assault is Sommerfeld's 36-year-old brother, who lives in Otsego, authorities said.

The two brothers got into a fight late Friday, authorities said. When deputies arrived, several people were attempting to help Sommerfeld.

The Sheriff's Office said people outside the bar initially told a deputy that Sommerfeld was not assaulted but hurt himself in a fall.

Deputies closed the bar, reviewed surveillance video and found witnesses who said Sommerfeld had been assaulted by a brother. The two were fighting when Sommerfeld was punched, "knocking him to the ground and rendering him unconscious," a statement from the Sheriff's Office read.

Sommerfeld was taken to HCMC with a "life-threatening head injury," the statement continued.

The suspect, who was not identified, changed into a clean shirt and left. He soon returned and told a deputy about his role in the fight.