The cause of the “devastating” death of a Bangor mother who crashed on Interstate 95 with her two children is still unknown.

Investigators say it is not yet clear why the station wagon driven by Liza Parker, 27, who was declared missing on Monday, crashed in the median of Interstate 95 in Old Town the night before.

“There have been no determinations made yet,” Lt. Sean Hashey, commander for Maine State Police Troop E based in Bangor, said Tuesday about the cause of the fatal crash. Police won’t know more until autopsy results come back from the state medical examiner, the vehicle is checked over and a crash reconstruction is done, he said.

Parker and her children were last seen in Bangor on Sunday afternoon. A passing tractor trailer driver reported the vehicle in the trees at about 1:30 p.m. Monday. Investigators believe that Parker’s vehicle went off the left side of the northbound highway on Sunday night and hit a dip created by an emergency vehicle crossover, which cause the vehicle to go airborne, flip over and land on its side.

The children were found alive — still strapped into their car seats — on Monday afternoon inside the crushed vehicle that was on its side, authorities said. The vehicle was found down an embankment and was not visible to most drivers.

Her children, Mason Worcester, 5, and 1½-year-old daughter, Tiaona Robinson, suffered only minor injuries in the fatal crash. Both were taken to Eastern Maine Medical Center. Worcester was released on Monday, a hospital spokesman said. No information about the condition of Parker’s daughter was available.

The stress has been hard on Parker’s family, her uncle Rodger Dow of Danforth said Tuesday.

“This is a very devastating emotional roller coaster ride,” Dow said.

Parker was the only niece in a large family and “was cherished by so many,” her uncle said.

“We are currently taking care of personal matters that we need to attend too and to get the kids home,” Dow said.

Parker was reported missing after she failed to show up for a scheduled meeting with Parker’s former husband in Howland.

“She had a heart of gold,” Lorie Friel Land, 57, of Woodville said of Parker, whom she met at Mattanawcook Academy when Parker was a teenager. “It’s just so hard, hard to believe.”