A man and a woman were found fatally shot on the Chicago Skyway Wednesday morning, NBC-affiliate WMAQ reported Wednesday.

According to Chicago police, the killing was likely a domestic-related murder-suicide. The woman was found with several gunshot wounds on her body, while the man was found with one gunshot wound to the head, Chicago police reported. Both of their bodies were discovered on the eastbound lanes of the Skyway, causing them to be closed for over two hours. Police said the shooting occurred around 4:15 a.m.

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The causes of death are unknown at this time, according to the Chicago Sun Times

In a 2015 report, The Violence Policy Center reported that more than 1,200 people lost their lives to murder-suicides in the United States the previous year. Ninety-three percent of the perpetrators used a gun. The National Violent Death Reporting System (NVDRS) under the Centers for Disease Control (CDC) defines murder-suicide as “a dramatic, violent event, in which a person, almost always a man, commits one murder or multiple murders, and then shortly after commits suicide.” Most perpetrators use guns when committing a murder-suicide.  

“What makes these acts particularly disturbing is that they often involve more than one person and often involve a family,” the study said. “Yet outside of high-profile mass shootings, the phenomenon of murder-suicide usually garners little public attention as a significant contributor to gun-related death and injury.”

Murder-suicides commonly occur because the perpetrator had a “life crisis” prior to committing the murder, according to the NVDRS in 2015, as reported by the Washington Post. Almost 80 percent of murder-suicides happen within two weeks of a crisis. More than 70 percent of murder-suicides occur after problems with an intimate partner arise.

The NVDRS investigated to link cases involving murder and suicide. In the past, murder-suicide rates have been hard to track because the suicide and murder aspects were investigated separately. In their studies, they included 32 states with cases dating back to 2003, amounting to 730 murder-suicide occurrences.

Out of those 730 cases, the NVDRS found that 93 percent of the murderers were men, with two-thirds of all case perpetrators being white men. They also found that many of the perpetrators were treated for mental health issues, often including depression.

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The 2015 study found that since domestic violence often plays a role in murder-suicide, state-level task forces to prevent domestic violence would be helpful in understanding and preventing murder-suicides. Changes in gun-control could also reduce murder-suicides, possibly lowering these instances to domestic injuries, said the report.

The apparent domestic-related murder-suicide case that occurred in Chicago Wednesday morning is still developing. 

UPDATE: Thursday, June 22, 2017 at 8:57 a.m. EDT: The identities of the man and the woman have been released. Lisa Fischer, 49, and Christopher M. Pena, 30, were the victims. Fischer got out of the car and Pena shot her multiple times. Afterward, he shot himself in the head, according to the Chicago Sun Times.