A man who was taken in by a Queens family when he needed a place to stay returned the kindness with unspeakable horror — setting the home ablaze in a gasoline-fueled inferno that not only killed him but also two of his host’s family members, including a 6-year-old girl, police sources and family said Thursday.

David Abreu Nuñez, 23, went off the rails inside the Moreno family’s two-story Elmhurst home on 93rd Street Wednesday afternoon, sparking the top-floor blaze after he was asked to pack up and go.

“We were helping someone and they were asked to leave because we found out certain things about that person and he just lost it,” said homeowner Raul Moreno, referring to Nuñez. “And this is the price we pay for helping somebody.”

Moreno said that Nuñez was a friend of a family member and had been staying at the home since Monday.

“He had no place to go. He was kicked out of his room or his apartment or something like that,” Moreno said. “He had no place to go, so we were like, ‘Stay here for a couple of days, we’ll help you find a place.’”

Moreno added: “Then we found out his past and we just asked him to leave because we had kids in the house.”

Nuñez had “mental issues,” Moreno said, claiming, “He would fabricate a lot of lies … things just didn’t add up. It made us very suspicious.”

“We just asked him to leave in a nice manner. We didn’t force anybody. I just asked him, ‘It’s time for you to leave’ and he just lost it.”

After the blaze, the FDNY found a five-gallon gas can on the floor where the fire started, sources said.

The two-alarm fire left Nuñez, Emma Dominguez, 6, and her 76-year-old grandfather, Claudio Rodriguez, dead, police sources said.

Emma’s mom, 35-year-old Elizabeth Rodriguez, and Emma’s 10-month-old brother, Liam Dominguez-Rodrigo, were critically injured, the sources said.

“Both of the kids were upstairs and he just ran up there, threw gasoline and set everybody on fire,” said Moreno, adding, “I just feel hatred.”

The Rodriguezes and Dominguezes are the Morenos’ relatives from the Dominican Republic and had been on summer vacation, staying at the family’s home since earlier this month, according to Moreno.

Another relative broke down outside of the fire-ravaged home Thursday while speaking to reporters.

“Sadly, sometimes the more you try to help, the more harm you can actually cause,” Anthony Moreno, speaking in Spanish, said outside the home.

“God willing those in the hospital will recover,” Anthony said. “There is no way to bring back those who died.”

Anthony said that Emma “liked to dance, play, tell jokes, watch videos on YouTube, put on princess dresses like any normal little girl,” while Claudio “loved his whiskey with family, a glass of wine, he loved to walk everywhere and explore New York.”

The injured, who suffered burns over 70 percent of their bodies, remained hospitalized at Manhattan’s Weill Cornell Burn Center.

“The boy is still in the hospital. We’re fighting and praying,” Anthony said.

Fire marshals determined Thursday that the blaze was incendiary, caused by “an ignitable liquid” that was “used as an accelerant,” an FDNY spokesman said.