A man and a 6-year-old boy were stabbed while they were sitting on a bench in Chicago's Lincoln Park neighborhood Sunday night.

At 10:24 p.m., the boy and the 27-year-old man were walking in the 2700 block of North Sheffield Avenue, between Diversey Parkway and Schubert Avenue, when a man they didn't know approached, police said.

The man became aggressive, pulled out a sharp object, and started a fight, police said.

The 27-year-old man was stabbed in the left arm, while the 6-year-old boy suffered a minor laceration to the back, police said.

Both were taken to Advocate Illinois Masonic Medical Center in good condition.

The attacker fled on foot, heading south, police said.

No one was in custody Monday morning. Belmont Area detectives were investigating.