Two men assaulted a man walking down the 4100 block of Eisenhower Ave. from behind, hitting him on the back of the head before fleeing, according to authorities. 

The duo struck at about 8:45 p.m. on June 6. They approached from behind and punched him, said Ashley Hildebrandt, department spokeswoman. He was uninjured in the assault, she said. 

Police dont know what prompted the attack. The two men remain at large, authorities said.