VISTA, Calif. -- A motorist whose blood-alcohol level was more than twice the legal limit when he crashed a Lexus into cars and a big rig on Interstate 5 in Oceanside, killing the 9-year-old daughter of a woman he'd been dating, was sentenced Monday to four years in state prison.

Michael J. Wright Jr., 24, pleaded guilty on Dec. 7 to gross vehicular manslaughter while intoxicated and could have been sentenced to a maximum of 11 years behind bars under the plea agreement.

Deputy District Attorney Jodi Breton said Wright's blood-alcohol level was estimated to be .17 to .18 percent at the time of the 1 a.m. crash last Aug. 3 that took the life of Violet Rosenquist, who was riding in the rear passenger seat of the 2006 Lexus.

The girl was pronounced dead at Rady Children's Hospital in San Diego. Her 3-year-old sister escaped injury.

The crash occurred after the defendant and the girls' mother left a post-memorial service gathering at which both consumed alcohol, Breton said. His girlfriend was passed out in the front seat, she said.

Wright, from Commerce in Los Angeles County, failed to notice in time that vehicles ahead of him were slowing down and abruptly swerved to the right, crashing into a Dodge Caliber, hitting a Honda CRV and slamming into the left rear of a big rig, according to the California Highway Patrol.

The driver of the Dodge suffered minor injuries, while the Honda's driver was taken to Tri-City Medical Center with moderate injuries, the CHP reported.

Wright and the victim's mother had been dating for eight to 10 weeks when the accident happened, Breton said.

Vista Superior Court Judge Daniel Goldstein sentenced the defendant to the low prison term because he had no previous criminal record, Breton said.