MILWAUKIE, Ore. -- A man who crashed his car on Interstate 5 in Washington and told police he killed someone is facing charges for shooting and killing his ex-wife's friend in Milwaukie.

The suspect, 62-year-old Gregory Sieberg of Milwaukie, was driving on I-5 near Ridgefield Sunday evening when he crashed his car into a barrier on the northbound side of the freeway at the Ridgefield Port of Entry.

Sieberg was trapped but uninjured after the car rolled and landed on its top, Washington State Patrol reported.

When officers arrived, the man told them, "I just killed someone," according to Trooper Will Finn, spokesman for WSP.

Meanwhile, Clackamas County deputies responded to a reported shooting near the corner of Southeast River Road and Torbank Road in the Oak Grove neighborhood.

They found a woman dead with a gunshot wound in the back of her neck. She was later identified at 53-year-old Melissa Elaine Vargas of Gaston, according to the Clackamas County Sheriff's Office.

Deputies talked to Sieberg's ex-wife, 61-year-old Debra Kusch-Siegberg, who lives at the home. She said Sieberg was upstairs at the house when he came downstairs, shot Vargas once then shot at Kusch-Siegberg multiple times.

Kusch-Siegberg said she ran to a neighbor's house and called 911. Siegberg drove away before police arrived.

Vargas was an acquaintance of Sieberg and Kusch-Sieberg but not a relative, police said.

Siegberg was cited for DUI and taken to a hospital. He was then moved to the Clark County Jail on a temporary felony warrant for homicide, Finn said.

Anyone who has information about Sieberg or the homicide investigation was asked to call the Sheriff's Office Tip Line at 503-723-4949.