A Bronx dad murdered in broad daylight on a Bronx street was shot in front of his 2-year-old son by a man known to the child’s mom, police said. 

Marquis Lane, 31, was with his toddler son as he argued with the woman at the corner of Park Avenue and East 167th Street in Morrisania minutes before 9 a.m. Tuesday, cops said. 

The gunman suddenly approached and opened fire — sending him scrambling under a car and striking him in the chest, according to cops and his grandmother. 

“I understand he was outside and they were arguing and the guy came around shooting and he went underneath the car, to try to avoid it,” his 75-year-old grandmother, Helen Hannibal, told The Post. “That’s where the police found him at. That’s all I know.”

Lane was rushed to Lincoln Medical Center, where he was pronounced dead. 

The suspect fled after the shooting, and so did the child’s mom. 

“I don’t know that woman,” said Hannibal, a retired home health aide. “I don’t want to know her.”

Lane worked in construction and leaves behind four kids, according to his grandmother. 

“It’s enough that it happened right on the corner,” she said. “He came over here to die, and that hurts, you know? If he just came upstairs in my house … Instead, he just tried to see his kid. He loves his kids.”

Lane was shot just blocks from the home he shared with his grandmother. 

“He was my grandson and I love him. He was a great father,” she said. 

“He would go shopping for me and make sure I was OK,” the woman added. “I’m going to try to survive as long as God lets me.”

Marquis’ father is “not well” after losing his son, the grandma added.

“That’s his only child and he died,” she said.