Four people were killed and seven were hurt in stabbings in northern Illinois on Wednesday, authorities said.

A suspect is in police custody and was being questioned, according to the police chief in Rockford, Carla Redd. She said one of the people who was wounded remained in critical condition.

Redd said police had received a medical call at 1.14pm, followed by additional calls for police and paramedics. Three people died at the scenes. The fourth died at a hospital.

“We don’t believe there’s any other suspects that are on the run or at large at this particular time,” Redd said. “Right now, we don’t have a clear motive as to what caused this individual to commit such a heinous crime.”

Redd said residents in the area were being asked to review their home surveillance camera footage for anything related to the attacks.

Rockford’s population is about 150,000, 90 miles north-west of Chicago. The violence came days after a teenage employee of a Walmart in Rockford was stabbed and killed inside the store.

“Today, we are shocked by another horrific act of violence against innocent members of our community,” said the mayor of Rockford, Tom McNamara.

The mayor wrote on the city’s Facebook page that “multiple jurisdictions” were “working on multiple crime scenes to develop an understanding of what transpired in an effort to prevent this from happening again”.

Rockford police initially said five people had been injured; a public information officer later said that that two more victims were among those hurt.

The suspect, a 22-year-old man, was arrested by a Winnebago county sheriff’s deputy after officers were called to a reported home invasion, Sheriff Gary Caruana said.

“The young lady ran from him,” Caruana said of one of the survivors. “She got some stab wounds in her hands and her face. She is in serious condition. One of the good Samaritans stopped to help her out. He did get some stab wounds. He is being checked out.”

Eric Patterson, a Rockford resident, said he was struggling to make sense of the violence on his street.

“You can’t rationalize this,” Patterson told the Rockford Register Star. “It’s almost like playing a video game, but it’s reality. It makes no sense. It’s like Grand Theft Auto. ‘I’m going to run over the mailman here. I’m going to stab a couple people there. I’m going to go in this house over here.’”

Another resident, Vanessa Hy, told WREX-TV in Rockford that the experience of witnessing the arrest was unreal, “like a movie”.

“All of the sudden, we heard police run up on both sides of the house screaming ‘Stop! Get down!’” Hy told the station. “Then they ran into the backyard, and after a few minutes we saw them bringing the suspect down the driveway in handcuffs and he was very bloody.”

Cassandra Hernandez, another neighbor, told the Rockford paper that she was friends with one of the victims.

“You never expect this here,” Hernandez said. “We have such great neighbors.”