Updated

A woman sought after her two young sons were found alone along Interstate 90 in Idaho was arrested Tuesday night in the nearby Spokane area after an anonymous tip.

The telephone tip led Spokane County sheriff's deputies to a house where they found 27-year-old Shannon Marie Germanton of Washington state, Deputy Craig Chamberlin said. She was arrested on a local negligent driving warrant and booked into the Spokane County Jail.

The boys, ages 6 and 3, were placed in foster care after they were found earlier in the day along I-90 in Post Falls, near the Idaho-Washington border. The boys told deputies their mother ran out of gas and went for help while it was dark and raining.

Idaho authorities plan to pursue an arrest warrant for child abandonment and child neglect, said Sgt. Matt Street of the Kootenai County sheriff's office. Kootenai County sheriff's detectives planned to take their case to a local magistrate in Coeur d'Alene on Wednesday and seek an arrest warrant that would allow Spokane County to hold Germanton pending extradition to Idaho.

As law enforcement officers in northern Idaho and eastern Washington searched for the woman, Post Falls police called her cell phone and spoke to her several times, Street said. She was evasive about her whereabouts and kept hanging up, Street said.

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"There was no real concern about where the children were," he said.

Initially officers didn't know whether they were dealing with possible illness, foul play or abandonment, Street said. Exactly what happened "is yet to be determined until our detectives can get an interview with her," he said.

Street said he didn't know whether the woman was represented by a lawyer.

A construction supervisor found the boys sitting in the grass near a freeway construction site at 9:10 a.m. Tuesday, Kootenai County officials said earlier.

Investigators learned that Germanton was given a ride to a gas station between 6:30 a.m. and 7:30 a.m. She told the driver she had argued with her boyfriend and needed to get to a phone to call for a ride.

No car was found near the boys and no one was at home at her last known address, Kootenai County sheriff's spokesman Ben Wolfinger said.

"We don't know if she has a boyfriend," Wolfinger said. Germanton is divorced, he said.