A heartbroken man whose stepson was killed last night when a bus plowed through their Long Island home made a desperate attempt to rescue the boy but could not get to him in time.

Six-year-old David Granados was killed when a municipal bus crashed into their Hempstead home as he was preparing for bed. Authorities said the bus driver swerved and jumped a curb to try to avoid hitting a pedestrian and barreled into the crowded house.

Santos Herrera, 41, said he was in the kitchen cooking when he heard something that sounded like a bomb.

“It was like an explosion,” Herrera said. “I ran to check on my kids, and I couldn’t see them. All the doorways were blocked. We couldn’t get out of the house. “We were trapped.

“I needed to get out somehow, so I found a sledgehammer my friend lent me and I used that to break the window. I heard my son, Josue, yelling, ‘Daddy, Daddy.’ I called out to him and I pulled my son out of the window and outside. My other son was trapped on the floor by the bus. I could tell right away that he had died.”

Officials said the bus, a Nassau Inter County Express bus carrying about 20 passengers, was traveling westbound along Fulton Avenue shortly before 10 p.m. while a pedestrian was ambling across the street. Cops said the driver honked his horn several times.

Nassau police spokesman Insp. Kenneth Lack said the driver swerved right to try to avoid hitting the pedestrian but hit him anyway before jumping the curb and plowing into the house.

Inside, three adults and two children upstairs were unharmed.

But downstairs, where there were four adults and three children, David, 6, was killed, and his brother, Josue, was injured.

Oh my God, my children,” the boys’ mother screamed after what sounded like an explosion, according to Alida Gutierrez, a family friend who lives in the house.

“She was crying, I was crying. I didn’t know what to do. I feel so bad for the mother.”

Lack said no criminal charges would be filed against the driver or the pedestrian.

“There is no reason to believe at all that the driver was intoxicated or speeding,” Lack said.