Responding to a rising tide of city street violence that has resulted in four homicides in the last six days - including the fatal shooting of a Dorchester teenager outside a party yesterday morning - Boston Police Commissioner Kathleen M. O’Toole yesterday unveiled a five-step action plan designed to reverse the trend.

“I’m very troubled by the senseless tragedies that continue to plague us, particularly those involving our youth,” O’Toole said in a statement released by the department yesterday. “It is too early to determine whether this is another random spike in violence or if a pattern is emerging.”