A 50-year-old man ran into a burning Oshawa, Ont., home in an attempt to save people stuck inside, then became trapped himself before dying along with a mother and two children, according to a neighbour who witnessed the act of heroism.

Lindsey Bonchek, 36, and her daughter Madeline, 9, died in the blaze that gutted the two-storey downtown home. Bonchek's son Jackson, 4, was pulled from the fire but later died.

It seemed like an average morning for neighbour Lisa Henderson, who was waiting for the school bus with a group of kids on Monday when she heard someone yelling "Fire!"

Ben, Bonchek's son who was waiting on the house's porch for the bus, tried to run inside, but Henderson "couldn't let him," she said. "We didn't know where it was, where it started."

Quickly, the whole house went up in flames, she said.

Steven Macdonald managed to escape the inferno with his pregnant daughter, but ran back into the building to rescue others, Henderson said. He did not come out.

Seven others who were in the house at the time survived.

Henderson said she sought shelter on a school bus with her kids and Ben. They waited two hours as the fire raged inside.

Henderson focused on keeping an eye on Ben and helping Macdonald's daughter Alysha. "She's 30 weeks pregnant. So it was trying to keep her breathing, trying to keep her calm."

Neighbour Laura Green said that Macdonald ran into the home and he never came back out. (CBC)

Neighbour Laura Green was outside her home attending to a broken pipe when she heard people yelling and shuffling out into the street.

She said Steven Macdonald was "a decent guy" and a good neighbour in an area where everyone tries to "look after each other."

Green said she watched as he sacrificed his own life in an attempt to save those still inside.

"It was ... you can't even wrap your mind around it," she said.

"When everything first happened, he was trying to staunch the fire, but it had gotten out of control way too quick," Green told CBC Toronto from outside her home.

"Steve heroically ran back into the building twice. Once to save his daughter, and then again, to save another child," she said.

John Peerzada, who owns a grocery mart near the home, said the Bonchek children, who died in the fire, frequented his store and he enjoyed it whenever they stopped in. (CBC)

"Knowing that people died in that fire, and that you were essentially watching their last minutes, it's horrific to get your head around."

Separate GoFundMe accounts have been set up for the Macdonald family and the Bonchek family.

Community pulling together

When she heard about the tragedy, hair salon owner Cindy Tay, who works with Alysha Macdonald, said the salon pulled together, wondering how they could help Alysha.

"When I spoke to her on the phone yesterday she was in the hospital and all she had was a housecoat," Tay said. "She called me from someone else's cellphone."

The fire destroyed much of the house, leaving survivors with little, Tay said. "They all need clothes. they don't have anything anymore."

Tay said donations are piling up, calling the response "overwhelming."

People she doesn't even know have dropped off bags and boxes of supplies, she said. "There's someone coming with a truckload of stuff."

A fire gutted a two-storey Oshawa home, killing four people 1:04

The owner of a convenience store down the street from the home said Madeline and her younger brother would come into his shop a few times a week, usually to pick up a few groceries for their mom or to buy some potato chips.

"She was so good and she was always smiling," John Peerzada said.

He said he spent much of Monday thinking about the children. He would often stand outside his store, watching them walk home to ensure they made the trip safely.

"I wish I could have saved her life," he said.

Finding cause could take time

The Office of the Ontario Fire Marshal is trying to ascertain what may have caused the fire.

"Once we determine where the fire originated, then we can examine possible ignition sources," said Richard Derstroff, an OFM investigator.

"But it's going to take quite some time to excavate through all the debris."

Lindsey Bonchek, 36, and her two children — Madeline, 9, and Jackson, 4 — are dead. Lindsey and Madeline were trapped in the home and Jackson, who was pulled out, died later. (Lindsey Bonchek/Facebook)

A key element of the probe will be to try to determine if the house was up to code and equipped with working smoke alarms.

"Smoke alarms are a huge deal for us because we want to determine whether there was any lack of early warning," said Derstroff.