CNN  — 

Five people and an unborn child were killed Sunday after an early-morning shooting in Indianapolis’ northeast side, police said – an incident the mayor called “a mass murder.”

A juvenile was also in critical condition after being shot in the incident, which marks Indianapolis’ “largest mass casualty shooting in more than a decade,” according to Indianapolis Metropolitan Police Chief Randal Taylor.

IMPD police officers responded to a report of a person shot just before 4 a.m. Upon arrival, police came across “a juvenile male with apparent gunshot wounds,” IMPD spokesman Shane Foley told reporters.

Officers then received information that led them to another residence less than a block away, where they found five people – including a pregnant woman – dead with “apparent gunshot wounds,” Foley said.

“Despite the best lifesaving efforts provided by medical staff, both the female and the unborn child did not survive,” he added. “The juvenile male that was shot is expected to survive his injuries.”

Marion County chief deputy coroner Alfarena McGinty identified the victims as Kezzie Childs, 42; Raymond Childs, 42; Elijah Childs, 18; Rita Childs, 13; Kiara Hawkins, 19; and Hawkins’ baby.

While IMPD’s investigation is in its early stages, Foley said the multiple shooting “does not appear to be a random act.”

As of Sunday afternoon, police said they did not have any named suspects related to the shootings, but that they believed more than one shooter could have been involved.

“This morning, one or more individuals perpetrated an act of evil in our city,” Indianapolis Mayor Joe Hogsett told reporters. “While we’re still learning more about the circumstances that led to this incident, I want to be very clear about something: What happened this morning was not an act of simple gun violence. … What happened this morning was a mass murder.”

Hogsett said he is in contact with the United States Attorney’s Office for the Southern District of Indiana and the Indianapolis Field Office of the FBI.

“Federal law enforcement are coming for them, as I speak. Coming for them today, coming for them tonight, coming for them tomorrow and the day after that. Coming for them as long as it takes to find them,” Hogsett added.

CNN’s Laura James contributed to this report.