Police arrested a 12-year-old boy after he allegedly stabbed a man in the chest during a weekend altercation at a St. Paul bus shelter.

Paramedics took the 42-year-old man from the Sun Ray Transit Center to Regions Hospital, where he underwent life-saving surgery, said Steve Linders, spokesman for St. Paul police, who assisted Metro Transit police in finding the suspect. It happened about 9:15 a.m. Sunday.

The man is being treated for injuries that have now been determined to be non-life threatening, said Howie Padilla, Metro Transit spokesman, on Monday.

The incident apparently began when two males with the 12-year-old got into an altercation with the 42-year-old, Linders said. The verbal altercation became physical, according to Padilla.

The 12-year-old punched the man, who started to chase the boy, Linders said. Police found the man wounded on the ground.

The suspect was discovered nearby, in the area of Conway and Pedersen streets, police said.

A passerby told police about seeing the suspect throw an object onto the roof of a nearby business. Firefighters responded with a ladder truck, and Metro Transit and St. Paul officers found a bloody knife on the roof, Linders said.