The blaze was reported around 5 a.m. at a four-family apartment building in Hartland, which is about 26 miles west of Milwaukee. Fifteen fire departments and nine police departments responded to the scene and worked to rescue people from the building and its balconies, Hartland police said at a news conference.
An "active criminal investigation" is now underway, police said. Asked by a reporter if there's any indication the blaze was started on purpose, police responded that it's "very early on in investigation stages -- that’s what we're looking into."
The victims' names and ages were not immediately released.