CONCORD — Fatal motor vehicle accidents in New Hampshire are up 30 percent over last year despite fewer collisions and after an unusually safe spring and early summer, prompting N.H. Department of Safety officials to issue warnings about unsafe driving practices.

“New Hampshire has experienced 71 fatal crashes thus far this year (through Sept. 9), compared with 54 during the same period last year,” said Commissioner of Safety John J. Barthelmes. “That is an increase of more than 30 percent, resulting in the deaths of 77 people, compared to 57 last year at this time.”

The total fatalities does not include the death of Laurel Fleet, 58, of Salem, who died in a crash with a tractor-trailer truck Monday on Route 111 in Salem.

The increase in fatalities occurred even as the number of crashes and the number of crash injuries is down, Barthelmes said.

The number of reportable crashes this year through Sept. 9 totals 15,058, compared to 17,546 for the same period last year. The total number of injuries in crashes this year is 5,936, compared to 6,913 for the same period last year.

“We have no immediate explanation of why fatalities are up while the number of crashes and injuries are down,” said Col. Robert L. Quinn, director of the Division of State Police. “But there is no mystery about the causes of serious crashes: speed, driving under the influence of alcohol or drugs, aggressive driving and driver inattention.”

Col. Quinn urged drivers to slow down and avoid dangerous activities such as texting and talking on cell phones while driving.

“Texting while driving is illegal in New Hampshire, but any activity that distracts a driver is dangerous,” he said.

Col. Quinn also encouraged drivers to wear seat belts at all times. He said air-bag systems are designed to work in tandem with seat belts. Many people were killed in otherwise survivable crashes because they were not wearing seat belts and were ejected from vehicles, he said.