A woman and a suspect in the killings of four members of the same family in Romeoville, Illinois, died after a police chase and vehicle crash, the Oklahoma State Bureau of Investigation said.

The vehicle -- believed to be driven by suspect Nathaniel Huey, Jr. -- crashed on Interstate 44 in Catoosa, Oklahoma, at the end of a police pursuit.

"(An officer) approached the vehicle and removed a female passenger, who was transported to a local hospital. She later succumbed to her injuries," the bureau said in a statement.

Officers heard what were believed to be gunshots as they approached the wrecked vehicle. Both the woman and driver, believed to be Huey who died at the scene, had a gunshot wound, police said.

Authorities have not released the name of the woman or explained her connection to Huey. "The Oklahoma Office of the Chief Medical Examiner will determine positive identification and cause of death for both individuals," the statement said.

Huey was named as a suspect in the murders of a family of four found shot to death in their home in Romeoville, about 30 miles southwest of Chicago, on Sunday.

The slain family members -- Alberto Rolon, 38; Zoraida Bartolomei, 32; and their two boys, ages 7 and 9 -- were found with gunshot wounds in the home Sunday night after a relative reported one of them didn't show for work, authorities said.

Hours after discovering their bodies, police identified Huey as a suspect in the case and an unnamed female as a "person of interest," Romeoville Deputy Police Chief Chris Burne said at a news conference Wednesday.

Evidence revealed a connection between the suspect and the victims, as well as a "possible motive," Burne said, without elaborating.

The female person of interest was reported missing and endangered by family members on Tuesday evening. She was then entered into the Law Enforcement Agencies Data System, a police communications and information network, Romeoville police said.

Later that night, Romeoville police released a statewide bulletin to law enforcement agencies that said Huey was a "credible suspect in the investigation," Burne said.

License plate reader alerted police to car, authorities say

On Wednesday morning, police in Catoosa -- roughly a 650-mile drive southwest of Romeoville -- received a license plate reader alert notifying them that Huey's vehicle was in their jurisdiction, according to Romeoville police.

Catoosa police spotted the vehicle and "attempted to conduct a traffic stop," but the driver tried to flee, and the vehicle crashed and caught fire, Burne said.

Officers on the scene then heard "two noises believed to be gunshots," Burne said.

The investigation is active and evolving, Burne said.