Driver inattention led to a fatal crash on Petaluma Hill Road that killed the driver's mother and injured his three siblings, the CHP said.

Eighteen-year-old Sebastian Hollingworth of Santa Rosa apparently was looking down at money in his lap as he drove about 60 mph on the thoroughfare Friday night.

When he looked up, he saw that he'd drifted into the opposite lane, CHP Officer Jon Sloat said.

The teen pulled the 2004 Chevy Trail Blazer to the right and lost control. North of Hunter Lane, near the Gables Wine Country Inn, the vehicle ran off the roadway and hit a tree, hit a second tree, rolled and stopped in a drainage culvert on its roof.

Shelli Shimmel, 43, died in the 8:30 p.m. crash.

A six-year-old sister remained hospitalized Monday at Children's Hospital in Oakland. Hallie Shimmel was in a medically induced coma and was steadily improving, the CHP reported.

She and siblings Jane Hollingworth, 16, and Shayne Hollingworth, 13, were taken to Santa Rosa Memorial Hospital. The young girl and 13-year-old reportedly had major injuries.

Hallie Shimmel was stabilized and flown to the Bay Area hospital for further treatment.

The older siblings weren't hospitalized at Memorial Monday.

Sebastian Hollingworth had minor injuries from the crash.

The speed limit in that area of Petaluma Hill Road is 55 mph.

2017 Recreational Abalone Season at a Glance

April and November now closed to the harvest of red abalone

Season open May 1 - June 30, Aug. 1 - Oct. 31

Fishing permitted 8 a.m. to half-hour after sunset daily

Season limit is 12 per calendar year, reduced from 18 last year

Only 9 abalone may be taken from waters south of Mendocino County

Daily limit is 3 abalone

Minimum size is 7 inches or more measured at the longest shell diameter

SOURCE: California Department of Fish and Wildlife