Police in St. Paul, Minnesota, are investigating a mass shooting that happened late Monday afternoon.

The St. Paul Police Department says officers responded to reports of shots fired shortly after 4:30 p.m. in the area of Fourth Street East and Earl Street.

Upon arrival, officers found four men suffering from gunshot wounds that appeared not to be life-threatening. 

Two of the victims were found in the intersection of Fourth Street East and Earl Street and the others were found behind a residence on the 1000 block of Fourth Street East.

Police say officers, K-9 and drone teams are searching the area for additional victims and to collect evidence.

Investigators are working to determine who is responsible for the shooting. On Tuesday afternoon, police said they believe the victims may have been shooting at one another. Police say the injured men are "being held" while they work to determine what led to the shooting.

The St. Paul Police Department says there is no threat to public safety.