DETROIT (BNO NEWS) -- Three of the four women who were found dead in Detroit last week were all working as escorts who advertised their services on BackPage.com, police said on Monday, raising fears of a possible serial killer.

The first victims were found at around 3 p.m. local time on December 19 in the trunk of a 2009 Chrysler 300C which had been parked in the driveway of a vacant dwelling on Detroit's east side. The victims were identified as black females, 23-year-old Renisha Landers and 24-year-old Demesha Hunt.

Two more bodies were found on Christmas Day, at around 1 a.m. local time, after the Detroit Fire Department responded to a vehicle fire on Lanette, also on the city's east side. After extinguishing the fire, the bodies of two black females, aged 28 and 29, were found in the trunk of the 1997 Buick LaSabre.

Detroit Police Chief Ralph Godbee said the first two victims had no outer signs of trauma to the bodies, and their causes of death are still being investigated. The other two victims were burnt beyond recognition due to the car fire, and their causes of death were also not immediately known.

"At this time, we are awaiting the Medical Examiner's final report for the determination of the cause of death for each of the females," Godbee said, adding that detectives are investigating all four deaths as homicides.

The chief said at least three of the victims were working as escorts and had posted ads on BlackPage.com, a website which is similar to Craigslist but allows postings for adult services such as escorts, massages, strippers and fetishes. "The link between the three females and this website specifically dealt with prearranged adult dating services," he explained.

Police stopped short of calling it the work of a possible serial killer, but Godbee warned people using the site to be careful. "We are not passing judgment on any individual who is utilizing this website, yet we felt it was imperative to alert the public that deciding to meet unknown persons via the internet, can be extremely dangerous," he said.

"We implore people to be careful and always let someone know exactly when and where that intend on meeting this person or persons, which should be in a public place. Our sole purpose is for the public to be cognizance of this website when engaged in adult activities," the chief added.

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