A 3-year-old boy in Brooklyn is fighting for his life after a bullet shot straight through his head, soaking his crib in blood, police sources said.

The heartbreaking shooting inside toddler Tharell Edward’s home on East 21st Street in Ditmas Park unfolded around 3:30 a.m. His live-in baby-sitter was with an unidentified 22-year-old male, who is her friend, cops said.

The two didn’t seem to be arguing, police added.

Authorities are questioning the unidentified man at the 70th Precinct, authorities said.

At the scene, police did not recover a weapon and authorities are seeking a search warrant to search the premises, cops said.

Police believe the gunfire that wounded the tot came from inside his home, said sources.

The child was rushed to New York Presbyterian/Weill Cornell Hospital and is now in critical, but stable, condition, sources said.

Terrell hasn’t had an easy life so far, family friends said.

He came into the world as a preemie, and his mother, Nichelle Edward, 40, has not been a stable part of his life, said family friend Jacintha Fleming. His father is out of the picture, she added.

Terrell was bitten two months ago by a pit bull that belonged to his mother’s boyfriend, Fleming said.

“I hope they take that child away. He’s not safe. She needs to be a better mother. He’s supposed to be safe in his own home,” said Fleming, who also lives in the building.

“He’s overcome a lot but I think it’s time for her to get into trouble because everyone keeps saving her a–. I’m not sorry for her. I’m sorry for the baby.”

The child’s cousin wiped tears from her cheeks as she spoke about the little him from a deli down the street.

“Terrell is very active. He wins you over with his smile,” she said. “He’s a strong kid. He’s been through a lot.”

A call to the Administration for Children’s Services was not immediately returned.

cgiove@nypost.com