WINTERPORT — This small town remains in mourning today after the sudden loss of two longtime residents who were killed when their car was crushed by a tractor-trailer on Route 1A Wednesday morning.

The best friends, Diane Kasparek, 46, and Suzanne Heiser, 56, died within minutes of their car being broadsided by a 1991 International tractor-trailer at about 9:30 a.m., according to police.

The two women, neither of whom was wearing a seat belt, received massive injuries when the 1996 Honda Accord was crushed by the oncoming tractor-trailer, driven by 29-year-old Steven Booker of Rockland.

Maine State Police Trooper Mark E. Nickerson, the primary investigator of the accident, visited the scene of the crash Thursday for what will likely be the last time.

While the accident technically remains under investigation, state police say its exact cause will remain unknown, he said.

“The truck’s driver said [Kasparek] was looking right at him as she pulled out,” according to Nickerson, who said the crash will likely be attributed to Kasparek’s failure to yield to oncoming traffic. “There is nothing evident that suggests that the truck driver did anything wrong. But, with what we have, we just won’t really know what happened. It looks as though she just didn’t see him coming.”

Police are considering a temporary real estate sign as a “possible initial obstruction,” but there was still room for the driver to see the oncoming truck, according to Nickerson.

“It certainly wasn’t the cause, but it could have been a contributing factor,” Nickerson said.

The sign, however, is in violation of state Department of Transportation regulations, which require that roadside signs on private property sit at least 33 feet from the center line of the road. Nickerson said Tuesday that the real estate sign sits just 26 feet from the center line.

Gregory Smaha, president of Free to See Homes, said the real estate company’s sign, which measures about 18-inches-high by 5-feet-long, has been up since August. He said the Bangor-based company placed the sign there at the request of property owner William Laverty.

When Laverty was advised of the regulation Thursday, he said he would either move or remove the sign as soon as possible.

“I guess I’ll do something with it,” said Laverty, adding that knowing the sign may have contributed to the fatal crash has weighed heavily on him. “I feel as bad as anybody. It was horrible.”

Laverty said he told the real estate company where to place the sign, but its placement was not meant to impair the vision of motorists.

Nickerson, who said he would submit his finished report to the Waldo County District Attorney’s Office, also said the color of the truck may have been a contributing factor. He said the green truck may have blended with the fir trees that line both sides of the road near the crash site.

But explanations of the accident will do little to help townspeople come to terms with the tragedy.

The mood was somber in the town office the day after the crash that claimed the two well-known women, according to Town Clerk Cheryl Johnson. She said the deaths have affected many in town, where the two families have lived for decades.

“It’s been hard,” said Johnson, who was very familiar with Heiser, who cleaned the town office. “It will affect people here for a while.”

Friends, neighbors and relatives of the women have turned out in numbers to support the families, according to Walter “Dutch” Heiser, Suzanne’s husband. Heiser, a local radio personality, said the two families, who lived on opposite ends of the village, have been friends for many years.

“They were very close,” he said of Kasparek and his wife. “They were best friends, and they will be missed.”

Before the fatal crash, Kasparek had picked up Heiser, who had been cleaning a cabin on Laverty’s property.

Police say Kasparek pulled out in front of the oncoming tractor-trailer, which was northbound toward Bangor. The truck, which is owned by Pen-Bay Transport Inc. of Rockland, had no mechanical defects that could have caused the crash, police said.

Both vehicles were destroyed.

NEWS reporter Doug Kesseli contributed to this report.