CHICAGO (WLS) -- Police say at least four people have been violently attacked in the past week on the city's North Side, but ABC7 has learned about more cases in Lakeview and Wrigleyville.Two victims say they were beaten, robbed and left seriously injured. Lucas Wittwer described how he was robbed and beaten steps from Wrigley Field."They punched me right in the side of the head and then I was on the ground," Wittwer said.Wittwer bears the scars of his assault and was briefly hospitalized."I check in and from there, I got three CT scans and an x-ray for my elbow," Wittwer said.Wittwer, a DePaul student, is the most recent victim of a series of brazen, late-night muggings in Chicago's Lakeview neighborhood."I never expected it to happen to me, and if it happened to me, I expected it to happen somewhere else, not next to Wrigley Field, in that nice of an area," Wittwer said.Chicago police issued a community alert this weekend to warn residents about the string of crimes.Seth Day says he was beaten and robbed on Halsted near Buckingham Place last week in an area bustling with bars and businesses.Day said he was beaten by a group of men who left him bloodied, then used his credit card nearby just hours later. Day says he believes Chicago police have surveillance video of his attack.Alderman Tom Tunney (44th Ward) spoke with police Monday. He said he is confident investigators will make progress."They've got plenty of resources out here, no one can say that there aren't the resources out here. But just putting puzzle together make sure we stop this," Tunney said.Police said all of the attacks happened late at night or early in the morning.Times and locations are listed below:3500 block of N. Clark on July 19 at 12:30 a.m.3300 block of N. Halsted on July 20 1:15 a.m.3200 block of N. Halsted on July 25 at 5:30 a.m.In the incident on Clark, the offenders were described as being four black men between 25-30 years old, and one white female, 25-30 years old.In the incident on the 3300 block of Halsted, the offenders were described as three black males and one black female.In the 3200 block of Halsted incident, there were three black male offenders, mid- to late 20s, 5'10"- 6'0" tall, with slim builds.