A man went on a stabbing rampage in a residential neighborhood in Northern Illinois on Wednesday afternoon, killing four people and wounding five in an attack that included a home invasion and involved multiple crime scenes, the authorities said.

Carla Redd, the police chief in Rockford, a city of about 150,000 some 80 miles northwest of Chicago, said at a news conference that a suspect had been taken into custody in the attack, whose motive was unclear.

Three of the four victims who were killed died at the scene, and the other at a hospital, the authorities said. Of those injured, one person was in critical condition at a hospital while four others were in stable condition.

The police did not name the suspect, but said that no one else was being sought in the attack. “We don’t believe there’s any other suspects that are on the run or at large at this particular time,” Chief Redd said at a news conference.

Sheriff Gary Caruana of Winnebago County said that among the victims was a woman who was running away from the suspect after an apparent home invasion. She and a person who had tried to help suffered stab wounds, the sheriff added. The woman is in serious condition while the man who intervened is in stable condition, he said.

The chief added that not all the victims had been stabbed, though she noted that no gunshots had been fired. A mailman was among the victims, the authorities said.

Four patients were taken to OSF Saint Anthony Medical Center in Rockford, a hospital spokesman confirmed.

Mayor Tom McNamara of Rockford said at the news conference that the episode had shaken the community, which was already reeling from another stabbing on Sunday in which a man was charged with murder in the killing of an 18-year-old employee inside a Walmart.

The killings came a month after police celebrated a report showing that violent crimes had dropped by 19 percent in the city last year, though homicides were up from 2022.

The police said that they had received calls for police and emergency assistance at about 1:15 p.m. on Wednesday.

Photos from the scene showed police tape blocking off large portions of a street in the residential neighborhood as fire and patrol vehicles arrived.

Vanessa Hy, a resident, told a local television station that she saw police taking the suspect into custody.

“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,” Ms. Hy told WREX 13.