WATERBURY, Vt. — State police will be more visible on roadways and the public is urged to buckle up following vehicle crashes that have killed eight people since Friday, public safety officials said.

Seven of the people killed were not wearing seat belts, Vermont Public Safety Commissioner Thomas Anderson said on Tuesday, a day after a crash killed four unbelted occupants of a car that hit a truck in Bridport.

While police can enforce driver laws, it’s really the operator’s responsibility to drive safely and to make sure occupants are buckled up, officials said.

“Drivers, do your job,” said Colchester police Chief Jennifer Morrison, who is president of the Vermont Association of Chiefs of Police.

Passengers also need to speak up if a driver is operating unsafely, she said.

Besides buckling up, drivers are urged to slow down, to not be distracted by cellphones and other devices while driving and to not drive impaired.

“It is really and truly a community responsibility,” Morrison said.

In the fatal crash in Bridport on Monday, the car crossed the center line of Route 22A and hit an oncoming pickup truck. The two people in the pickup truck, who were wearing seat belts, survived with non-life-threatening injuries. Other fatal crashes happened in Brownington, Milton, Royalton and Springfield.

The lack of seat belt use is the most common factor in fatal Vermont highway crashes, followed by impaired driving, state police said.

This year, 57 percent of occupants in fatal crashes were not wearing seat belts, about the same as at this time last year. To date 44, percent of operators in fatalities were suspected of driving under the influence of alcohol, drugs or both.

Republican Gov. Phil Scott is very concerned about traffic safety following the fatalities, Anderson said.