The New York mother who killed herself and three of her children by driving her minivan into the Hudson River reportedly may have had a change of heart in the final moments of the ordeal. 

Lashanda Armstrong, 25, packed her four kids into the family's minivan Tuesday night and drove off a boat ramp and into the cold and murky river, six blocks from her home in Newburgh. Armstrong's 10-year-old son survived by climbing out a window and swimming to shore. When police pulled the submerged van out of the water, they found the bodies of Armstrong and three of her children: Landon Pierre, 5, Lance Pierre, 2, and 11-month-old Lainaina Pierre 

Passerby Meave Ryan, who noticed the boy and drove him to a nearby fire station, said he told her his mother realized it was a mistake and tried to put the van in reverse, WNBC-TV reports. 

Ryan told the station that 10-year-old Lashaun Armstrong said his mother kept repeating, "I made a mistake, I made a mistake."

Ryan also said Laushaun told her that "she went into the back seat and held them all together and said, 'If I'm gonna die, you're all going to die with me,'" according to the station. 

Newburgh Police Chief Michael Ferrara said Thursday that investigators may never determine Armstrong's mental state when she drove her children into the river. He told The Associated Press that police are hoping anyone who witnessed the triple murder-suicide will come forward to provide more details.

The woman's sister, Darice Armstrong, told NBC's "Today Show" in an interview aired Thursday that Lashanda grew increasingly paranoid in the weeks before the tragedy.

She told the network that Lashanda "felt someone was watching her," and described to her sister how "lights in her home flickered on and off."   

Police say a domestic altercation occurred about 10 minutes before Armstrong drove into the river at approximately 8 p.m. Tuesday. A relative in Rockland County called police to report a domestic incident at Armstrong's apartment. By the time police got there, she and her children were gone. Authorities said there was no history of domestic violence at the address.

 A fire official said Wednesday that Lashaun probably had less than two minutes to escape. Ryan was driving by when she noticed the boy, traumatized and soaking wet, and took him to a nearby fire station. Firefighters and police quickly launched what they hoped would be a rescue mission. Divers found the minivan submerged in 8 feet of 45-degree water about an hour later, 25 yards offshore.  

Armstrong lived in an apartment in a gritty part of this humble river city. Several neighbors on Wednesday recalled her as an attentive mother who balanced care of her children with an outside job. They were shocked by the news.

"She was a very good mom," said Tina Claybourne, who lives nearby. "She took care of her kids. She always was with her kids."

Neighbors said they did not know the woman's name or where she worked. They said the children seemed energetic and happy and would play on the block and ride bikes.

"You know kids, they make noise, they play around," said Shantay Means, a downstairs neighbor.

The boat ramp was unguarded by gate or chain. There was no sign that anything tragic had happened save for a single teddy bear left at the end of a dock that runs alongside the boat ramp.

Newburgh, which has about 30,000 residents, sits on the western shore of the part of the river that runs south through New York State and eventually splits New York and New Jersey.

The Associated Press contributed to this report