Authorities are investigating the quadruple homicide at a fast-food restaurant and the fatal shooting of a pregnant woman in separate incidents which occurred within hours of each other on Thursday in one neighborhood in the nation’s third-largest city.

The spate of killings comes as the Chicago has tallied nearly 900 murders in the last 15 months.

Four male victims were found in or around the Nadia Fish and also Chicken restaurant at around 3:50 p.m. in the city’s South Shore neighborhood, according to the police.

Police said that a male suspect approached the restaurant and he fired shots. When the officers arrived at the scene, they found two of the victims inside the restaurant and one victim outside the restaurant, and a fourth unresponsive victim in nearby yard. Two of the victims in shooting were identified as brothers Raheem, aged 19, and Dillon Jackson, aged 20, and also the third victim was identified as Emmanuel Stokes, aged 28. The authorities had not yet released the name of the fourth victim.

Hours earlier, the police responded to an incident at an apartment about a mile from the restaurant in which a pregnant woman, aged 26, Patrice Calvin, was found dead with a gunshot wound in the head. No suspects were in the custody for either incident.

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On the late Thursday, a police spokesman Anthony Guglielmi said in a Twitter posting that the investigators believe that the shooting at the restaurant was "gang-related retaliation from another incident." A team of detectives were canvassing the area on Thursday evening and looking for private security video from the area businesses that may have captured portions of the incident, said Guglielmi. Following the shootings, the department also beefed up patrols in the neighborhood. With more than 760 murders in the last year, Chicago tallied more killings than the New York City and Los Angeles combined.

Through the first three months of the year 2017, murders have slightly decreased with the city recording of 123 murders through Sunday, compared to 136 at the same time in the last year, according to the police department data.

The bulk of murders have occurred in a few predominantly black and the Latino neighborhoods on city’s South and also West sides. Police department brass said the vast majority of the killings are tied to the gang-fueled drug trade in those areas.

In the recent months, police department has built a series of the data-driven support centers in some of the city’s most violent neighborhoods which use hyper-local video and also data to help officers more quickly respond to shootings and also help police predict where the next incident may occur.

Mrudula Duddempudi.