A fire that broke out Monday afternoon in a St. Paul apartment building likely was the result of arson involving an emotionally disturbed person, police said.

The only person injured in the fire was the suspect, who lived in the second-floor unit where the fire occurred and who was later taken to St. Joseph's Hospital for treatment.

Firefighters were called to the apartment building, in the 1100 block of Mackubin Street, about 2:30 p.m., St. Paul Fire Marshal Steve Zaccard said.

A district chief reported hearing gunfire and warned firefighters, but Zaccard said that officials have determined that no shots were fired at the crew.

The fire was quickly brought under control, he said.

Lamar Barber-Tallman, who lives on the same floor as the unit with the fire, said the man emerged from his apartment "covered in soot. It was in his mouth, in his teeth."

When he began acting strangely outside the building, police put him in a squad car and then transferred him to an ambulance.

There was some smoke damage in the hall outside the apartment, but residents eventually were allowed back into the building, Zaccard said.

Sgt. Paul Paulos, spokesman for the St. Paul police, said that the case has been turned over to the fire department for investigation as an arson.