AUGUSTA, Maine — Deadly weekend crashes claimed the lives of six residents and put the number of deaths on Maine roads at more than 50 percent above last year at this time, officials say.

“The six highway deaths bring the state’s total for the year to 46 compared to 30 deaths at this time a year ago — a 53 percent increase,” Stephen McCausland, spokesman for the Maine Department of Public Safety, said Monday in a statement.

Speed was a factor in nearly 59 percent of this year’s deadly crashes. At least one-third of the deaths involved alcohol and 15 percent involved teenagers.

“The Bureau of Highway Safety says speed has been a factor in 27 of the 46 highway deaths so far this year and alcohol is involved in, at least, 15 of the fatal crashes,” McCausland said.

Seven people between the ages of 16 and 19 and five young adults between 20 and 24 have died in crashes this year, Michelle Ward, a fatal accident system analyst with the Maine Bureau of Highway Safety, said Monday.

While the beginning of 2012 has started off with more road deaths, “Maine has had four exceptional safe years on the roads and last year was the safest year since 1959,” McCausland said.

The state recorded 136 traffic fatalities in 2011 — matching a benchmark set in 1959 — and last year’s figures showed a significant decrease from the 160 highway deaths in 2010, Ward said.

The 2011 highway deaths included “15 motorcycle fatalities, 16 teenagers, between the age of 16 and 19, 11 pedestrians, no bike and no moose and 15 commercial vehicle[s],” she said.

In 2009, 159 people died on Maine roads, and in 2008 the figure was 155.

In 2007, the state recorded 183 traffic fatalities, and in 2006 it had 188.

The deadliest year ever for Maine highway deaths was 1970, when 276 people were killed, McCausland has said.

The United States has seen a declining highway deaths trend that started in 2009, according to statistics compiled by the National Highway Traffic Safety Administration. In 2010, 32,885 people died in traffic crashes in the U.S. and in 2011 the number dropped to 32,310, the lowest number of fatalities since 1949, the agency said.

The weekend deaths in Maine included two men who were killed Friday night in a crash in Newfield. WCSH-6 of Portland reported that the victims were identified as Moses Gerry, who was driving the vehicle, and passenger Jonathan Seaman. Speed was a factor in the crash.

A Northport man died Saturday evening in what Maine State Police said was the second motorcycle fatality of the riding season.

Donald “Skip” Rogers, 64, had been riding a Harley-Davidson on Route 52 about 6:30 p.m. when he went off the road on a curve and flipped into a ditch, according to McCausland.

Rogers was not wearing a helmet and the likely cause of his death is head injuries.

“Alcohol is a likely factor in the crash,” McCausland said.

Road conditions were good at the time of the crash. Four state police troopers went to the scene.

In Sanford on Saturday, a Shapleigh woman died after a vehicle she was a passenger in was broadsided, according to police.

Marlene Lewis, 73, of Shapleigh was pronounced dead at the scene, Sanford Deputy Chief Tim Strout said Monday.

Shirley Clements, 70, of Sanford, driver of the 1996 Toyota that Lewis was traveling in, was heading southbound on Main Street when she attempted to turn left into a shopping plaza, Strout said. A 2003 Chevrolet heading north slammed into the passenger door of the Toyota.

Clements was taken to Goodall Hospital in Sanford for a possible broken leg, Strout said. The occupant of the other vehicle was not injured.

Police say a Belmont man died after his car went off Route 32 and struck a telephone pole in Windsor just after noon Sunday

Timothy Simmons was driving south on Route 32 when his car left the road, traveled along a ditch and struck the pole. The car ended up on its roof.

State police say speed appears to be a factor and the 44-year-old Simmons likely died instantly. Alcohol is not considered a factor but the accident remains under investigation.

Simmons was wearing his seat belt.

Authorities called off the search Sunday night for a Skowhegan woman presumed killed Saturday night when her car drove into a river in Fairfield.

Divers probed the murky water near a bridge until Sunday night and did not find the body of Cora Marley, 62.

Fairfield police Sgt. Matthew Bard says a warden’s service aircraft would fly over the area Monday, but it was unlikely divers would return to Martin Stream, tributary of the Kennebec River.

Marley is the sister of former state Sen. Ken Gagnon.

Witnesses driving behind her said her vehicle was driving erratically and the brake lights didn’t come on before the car veered into the water.

In addition to the six fatal accidents on Maine roads, authorities said three people found dead in a Jeep in a bog in Windsor over the weekend apparently were overcome by carbon monoxide fumes as the driver tried to accelerate out of the mire.

Officials identified the victims as 41-year-old Reginald Gay, his wife, 33-year-old Samantha Gay, both of Windsor, and 22-year-old Luke Thompson of China.

Authorities say it appears the vehicle got stuck and exhaust fumes entered the enclosed passenger compartment.

The state medical examiner’s office has ordered additional toxicology tests to confirm the cause of death.

BDN writers Ryan McLaughlin and Abigail Curtis and The Associated Press contributed to this report.