Four people were found dead and seven others were injured in a stabbing rampage across multiple areas in Rockford, Illinois, on Wednesday afternoon and a suspect is in custody, police say.A 15-year-old girl, a 63-year-old woman, a 49-year-old man, and a 22-year-old man were killed and five others who were injured were taken to hospitals with "serious injuries," the Rockford Police Department said in a news release Wednesday evening.A mail carrier was among those killed, according to police and the U.S. Postal Inspection Service.Five people were injured in the city of Rockford and two people were injured in the jurisdiction of Winnebago County, Rockford police spokesperson Michelle Marcomb told CNN. The suspect is in custody and police don’t believe there are any other suspects at large, Rockford police Chief Carla Redd said Wednesday at a news conference."We don't have a clear motive in regard to what caused this individual to commit such heinous crimes," Redd said.Police received a call for medical help at 1:14 p.m., followed by additional calls for assistance, Redd told reporters.Officials responded to multiple addresses in the area of Holmes Street, Winnetka Drive, and Cleveland Avenue, according to a police statement. The suspect, a 22-year-old man, was taken into custody by 1:35 p.m., police said.Winnebago County Sheriff Gary Caruana said county officials received a report of a home invasion after 1 p.m. He said a young woman had run from the suspect."She got some stab wounds in her hands and in her face," he said. "She is currently at a hospital, and she is intubated. She is in serious condition."Caruana said a good Samaritan who stopped to help the woman also suffered stab wounds. "He's fine. He is being checked out," the sheriff said.Police said not all of the victims were stabbed, nor did they have any gunshot wounds, but did not indicate how the other victims died or were injured.Police urged residents to look at their security and doorbell cameras for any video footage related to the incidents, and to submit any tips to police or anonymously through the Rockford Area Crime Stoppers.Rockford is roughly 90 miles west of Chicago and has a population of about 150,000 people.Mayor Tom McNamara said he was "totally shaken by this act of violence and the impact that it’s having now on multiple families’ lives."There will be counselors on-site at Flinn Middle School on Thursday and Friday to help those individuals and families that have been impacted, he said."It's hard to grasp how this could happen and how emotional and raw the community is tonight," the mayor said in a Facebook post. "As a dad, a son, a husband, the Mayor and a Rockford supporter, my heart is breaking for those who have lost their lives, their families and our community."Federal, city and county officials are aiding in the active investigation, police said.CNN's Emma Tucker, Jennifer Feldman and Andy Rose contributed to this report.