Six people, including four children, were killed early Wednesday when a blaze tore through a Harlem NYCHA apartment building, police and fire officials said.

The flames erupted in a fifth-floor apartment of the seven-story Fred Samuels Houses on Seventh Avenue near 142nd Street in Harlem at about 1:40 a.m., authorities said.

“As soon as I saw the flames, it was literally in one apartment. They were as vibrant and destructive as possible. It wasn’t pretty. I heard glass breaking, kids yelling,” said Abdul Salaam, 25, who witnessed the fire from the street and called 911.

“As the fire is spreading, I heard actual voices screaming,” he added. “They were clearly in fear for their lives.”

The victims — an adult man, adult woman, two young girls and two young boys believed to be family members — were declared dead at the scene, police said.

The fire appears to be an accident, though a full investigation of the cause was underway, police said.

When the flames were extinguished, FDNY cleared the building and discovered the six bodies, police said.

Investigators were working to determine how the fire started.

One resident said he and his 75-year-old mother, who live on the fifth floor, fled down a fire escape.

“There was so much smoke, you couldn’t even see. We went to the back fire escape,” said Geraldo Morales, 55.

“The smoke — I got asthma — so it was like I was getting suffocated. My mother is 75 years old and the smoke just hit us,” he added.

A neighbor fondly recalled the family’s young girls as little “angels” after the blaze.

“The daughters were all beautiful kids. I never knew them by name. Everyone knew one another from coming and going,” said Eric Allen, who lives on the fourth floor.

“Two days ago, I picked my girls up from school and the two girls were coming out the building and said to my daughter, ‘Oh my God, this jacket so nice,’” he added. “They were beautiful kids.”

During the blaze, Allen said, he heard them struggle to get out of the apartment.

“As the fire was burning, I was hearing one of the little girls screaming,” he said.