SACRAMENTO -- Rocked by four serious crashes involving highway workers and law officers, including two in the Sacramento region, California safety officials are issuing a warning about what they consider a lethal mix -- road construction and distracted driving.

Fifteen people including several Caltrans workers, a California Highway Patrol officer and six community service cleanup crew members -- were injured in highway crashes over three days in mid-September. The incidents have prompted state officials to implore drivers to keep in mind they may have to slow down, move over and even come to a stop on state highways at times because of roadwork or other issues.

"Each driver behind the wheel has to be prepared," said Wayne Zieseman of the state Office of Traffic Safety. "People feel they can still drive at maximum speeds. They are distracted. They are not getting ready for a change of (roadway) conditions ahead."

Two state Department of Transportation workers and two occupants of a private vehicle were injured Sept. 16 in Mendocino County when the private vehicle crashed into a Caltrans truck that had stopped by the road so workers could remove a dead deer.

That day in Butte County, a contractor on flagging duty was seriously injured when he was struck by a car that had swerved to avoid the vehicle in front, which was slowing for the construction zone.

A CHP officer on Interstate 80 in Auburn is credited with saving a Caltrans maintenance worker Sept. 17 by positioning his cruiser, with lights on, in the path of a car that was approaching the construction worker at 65 mph. The car did not brake and rear-ended the CHP vehicle. The worker, who was picking up debris in the slow lane, was uninjured. The CHP officer was briefly knocked unconscious and returned to work Wednesday.

On Sept. 18, in Diamond Bar in Southern California, two Caltrans workers and six members of a construction crew were injured when a big rig drove into their work zone. The big rig driver was also injured in the crash.

Caltrans spokesman Mark Dinger said distracted driving, including illegal cellphone use, continues to be considered a key cause of "cone zone" crashes. Caltrans has 732 major construction contracts out statewide, 69 of them ongoing in the Sacramento and Northern California area, he said.

Overall, construction zone fatalities are down 56 percent since 1999, when state and federal officials launched "Slow for the Cone Zone" programs. The state has implemented higher citation fines for drivers who fail to slow in construction areas. More recently, California law officials have put more emphasis on enforcing the state's "move over" law, which requires drivers to move one lane over or slow down when they pass police, Caltrans or other official vehicles with amber lights parked beside the road.

Despite those laws, state officials say data indicate road maintenance and construction jobs are among the most dangerous occupations nationally. Since 1927, 180 Caltrans employees have been killed while working.

"These incidents are a sobering reminder that we all must do everything we can to keep our highways safe," Caltrans Director Malcolm Dougherty said.