The death of a fourth motorcyclist in Minnesota since Saturday has brought the year’s fatality total for riders to 24, a 50 percent increase over this time a year ago, state safety officials said Wednesday.

“To be eight deaths ahead of last year at this point is very unfortunate,” said Megan Matthews, spokeswoman for the state’s Motorcycle Safety Center. “We’re hoping riders and motorists really take this to heart and take steps to help prevent more rider deaths this season.”

Of the 24 killed so far this year, 16 were in their 40s or older, according to data from the state Department of Public Safety.

Also, the data revealed, 11 of the fatal crashes occurred while motorcyclists were negotiating a curve. As for helmet use, 14 of those killed were not wearing one, seven were and a determination could not be made for three.

“Negotiating a turn … is a skill motorcyclists can master by taking a rider training course,” Matthews said. “There are courses available for more advanced riders, not just beginners.”

While requiring a helmet for adults is not the law in Minnesota, the state’s public safety officials are relentless in urging riders to don helmets and “brightly colored protective gear for visibility and protection,” Matthews said.

Drivers of other vehicles can also do their part and “give riders room, check blind spots, pay attention and drive at safe speeds. Motorcycles are smaller, so their speed and distance is more difficult to judge.”

The latest deadly crash occurred shortly after 6:30 p.m. Tuesday.

Killed was Guy M. Donnelly, 54, of North Branch, Minn., according to the State Patrol. Donnelly was heading north on Hwy. 95 along the St. Croix River when his motorcycle veered off the road, continued in a ditch for about 250 feet and crashed, the patrol said.

Donnelly was dead at the scene. The patrol said he was not wearing a helmet.

Other motorcycle fatalities since Saturday:

About 1 a.m. Saturday, Justin J. Posusta, 24, crashed near his Belle Plaine home, police said. The motorcycle kept going without its operator, went through a chain-link fence, rammed a home and punctured a natural gas line, according to police. The gas leak was quickly contained. Police said Posusta was not wearing a helmet.

About 9:30 a.m. Sunday in southeastern Minnesota, a motorcyclist attempting to pass a pickup truck on Hwy. 61 near Wabasha hit the turning truck, according to the patrol. Troy A. Malek, 45, of Oakbrook Terrace, Ill., was killed.

At roughly 2 p.m. Sunday in Sherburne County, a pickup making a turn at Hwy. 10 and Sherburne Avenue in Becker struck a motorcycle, the patrol said. Killed was Brett A. Behnke, 52, of Turtle River, Minn.

The patrol said Malek and Behnke were wearing helmets at the time.