Four people taken into custody in Milwaukee this week are considered persons of interest, police said, after six people were found dead inside a home Monday.

All four individuals were being investigated for their possible connection to what police have described as six homicides, police Chief Jeffrey Norman told reporters at a Thursday news conference.

No charges had yet been filed in there case as police continued their investigation, FOX 6 of Milwaukee, reported.

Police believe multiple suspects were involved in the killings, Norman said. The six victims' bodies were discovered after a 911 call was placed, he added.

6 ADULTS FOUND DEAD IN MILWAUKEE HOME IDENTIFIED, MULTIPLE-HOMICIDE INVESTIGATION CONTINUES

A homicide investigation got underway in Milwaukee this week after police found six bodies inside a home,

A homicide investigation got underway in Milwaukee this week after police found six bodies inside a home,

"On Monday, we became aware of a 911 call that was considered to be related to the investigation, but was not attributed to the address where the incident occurred. This 911 caller claimed that she was a victim of a shooting -- and that multiple other people were shot," Norman said. "The caller gave two different addresses in the vicinity of where the homicides occurred, near the area -- but neither one of them were on the 2500 block of N. 25th Street. The call was received approximately 12 hours prior to discovery of the victims."

Responding officers were able to locate the individual who made the 911 call, but determined she was not a shooting victim, the chief said. That individual remained under investigation, he added.

BABY, 6 MONTHS, SHOT AND KILLED IN ATLANTA; ‘THIS ONE HURTS,’ CHIEF SAYS

Milwaukee police said six recent deaths were being investigated as homicides.

Milwaukee police said six recent deaths were being investigated as homicides.

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The local medical examiner has identified the homicide victims as Charles Hardy, 42; Caleb Jordan, 23; Javoni Liddell, 31; Donta "Michael" Williams, 44; Michelle Williams, 49; Donald Smith, 43, FOX 6 reported.

It's unknown which day the homicides occurred, although they likely took place over the weekend, the chief said.

There has been a 155% increase in homicides in the city this January compared to last January, the medical examiner said Monday, 

Fox News' Stephen Sorace contributed to this report.