Police offered little new information Thursday about the murders of three children and a woman found shot to death earlier in the day in a red SUV parked off Interstate 55 in northeast Illinois.

Authorities said a 35-year-old woman, a 12-year-old girl, an 11-year-old girl and an 8-year-old boy were found dead in the vehicle, but they wouldn't release the victims' names, their relationship or other details of the shooting spree.

"We are withholding providing identification of who we believe the victims are until we can notify next of kin," Illinois District 5 Capt. Ken Kaupas told reporters at a news conference Thursday. "That has not been positively confirmed yet, but will be shortly."

He said the public has no reason to be concerned about a suspect at large and there was no manhunt currently under way. He didn't elaborate further, but said the victims appear to have been related.

A wounded man was taken from the scene and treated and released at Provena St. Joseph Medical Center in Joliet. Kaupas said he's being interviewed by investigators but isn't under arrest.

Channahon Mayor Joe Cook said the murders appeared to have been a case of domestic violence.

The crime scene was still being processed, according to Kaupas, and no charges have yet been filed, said Will County State's Attorney James Glasgow.

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The bodies were found in a vehicle parked off a frontage road of I-55 in Channahon Township, Ill. FOX affiliate WFLD-TV reported that the vehicle was registered to Stone Bridge Security, Inc. of Aurora, Ill.

Will County sheriff's deputies are assisting the Illinois State Police with the investigation.

Channahon is a community of approximately 11,250 people in northeast Illinois.

The Associated Press contributed to this report.

This is a developing story. Click refresh for more updates.

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