Minneapolis police are investigating the death of a 23-year-old man found lying fatally wounded in a south Minneapolis alley early Sunday with at least one gunshot wound.

His death Sunday afternoon at Hennepin County Medical Center marked the city's 21st homicide of the year and the second of the day.

According to police spokesman Sgt. William Palmer, officers in the Third Precinct were responding to an activation of their ShotSpotter system about 4:30 a.m. when the call was updated to a shooting in the 2700 block of 13th Avenue S.

There, they found the victim in an alley behind some homes.

The victim, whose name had not yet been released, was taken to HCMC in "grave condition," Palmer said.

The Hennepin County medical examiner's office will conduct an autopsy.

No one is in custody. Anybody with information is asked to call 612-692-8477.

The man's death, and a deadly stabbing on Sunday in north Minneapolis, were the city's 20th and 21st homicides of 2011.

On Sunday, a citizens' group called From Death to Life and residents of north Minneapolis held a prayer walk and vigil in the area of North Commons Park in remembrance of the city's homicide victims, including Quantell Braxton, 14, and Ray'Jon Gomez, 13, shot to death last week in the area. No suspects have been arrested in their deaths.