A couple from Wales were killed Monday when a pickup truck that was in the wrong lane hit the motorcycle they were riding on Route 113 in Hiram, Maine State Police said.

Patrick Vaillancourt, 67, and his wife, Margaret Vaillancourt, 64, were killed about 2 p.m. on a stretch of road with a slight curve, state police said.

“So far there is no explanation why the truck was in the wrong lane,” said state police spokesman Stephen McCausland. The Oxford County District Attorney’s Office will review the crash report, he said.

The driver of the pickup truck, Kenneth Bouffard, 33, of Hiram, was taken to Maine Medical Center in Portland, where he was treated and released.

The two deaths bring Maine’s total of motorcycle fatalities to 24 this year, compared with 11 people for all of 2014. There were four deaths during the Labor Day weekend.

Earlier Monday, state police announced that Randall Goslin, 40, of Farmington, New Hampshire, died at Maine Medical Center after a motorcycle crash in Lebanon.

Goslin’s motorcycle hit a utility pole on Route 202 near the New Hampshire border Saturday night. Troopers said alcohol and speed were factors in the crash.

On Saturday, Alexander Small, 21, of Richmond died after the motorcycle he was driving collided with a sport utility vehicle on Interstate 295 in Falmouth. Small was wearing a helmet.

Maine Bureau of Highway Safety reports show motorcycle fatalities ranging from 15 to 24 per year from 2005-12.

While it’s difficult to speculate why motorcycle fatalities have increased, more drivers are on the roads this year. Traffic spiked this summer as tourism rebounded in 2015, according to the Maine Turnpike Authority, including a record-breaking August, with more than 8 million passenger cars on the turnpike.

According to the Bureau of Highway Safety, riders without helmets account for about two-thirds to three-quarters of all motorcycle fatalities in a given year.

Under Maine law, helmets are required for motorcycle riders 18 and younger, and those with learner’s permits and first-year licensees. Maine required all motorcycle drivers to wear helmets in the 1960s and 1970s, but the helmet law was repealed in 1977.

McCausland said one of the Vaillancourts was wearing a helmet.

Staff Writer Joe Lawlor contributed to this report.