A quick-thinking mom hugged her daughter to deflect the blows of a deranged straphanger who pummeled the woman and 10-year-old aboard a Bronx train.

She was picking her daughter up from school last month when their lives were turned upside down.

The mother and child were standing on the packed 4:30 p.m. train when the crazed woman started punching them in the face and mouth,  she said.

“The whole attack was one train stop long, like a minute and a half, she got on at one stop, starting attacking us, and got off,” said the woman, who asked that her name not be shared.

She instinctively went into Mama Bear mode during the unprovoked attack on a northbound 5 train, she said.

“In the moment that she hit me, my daughter moved closer to me and I hugged her to protect her, so the lady was mostly hitting the back of my head,” she recalled of the terrifying attack, which happened Oct. 18 but recently made headlines when the NYPD released information about the incident.

“When we got on the train it was full, so we stood side by side against the closed doors,” she told The Post. “Because the train was full the lady also was standing close to us. The moment that the train doors closed, she at once started hitting us. When I got on the train I noticed she was looking at me but ignored her and I bowed my head. “

“It all happened so fast and it scared my daughter, she was crying and there was a lot of screaming. I hugged her trying to block the punches, I didn’t care if I was getting hit,” she added.

The violence came without a word, the mom noted.

“My daughter said [the attacker] had a little girl with her but I didn’t see that, it all happened too fast. It was unprovoked, she didn’t even talk to me beforehand, she wasn’t acting strange. … I don’t know what it was, if she had a bad day or something,” she said.

Unbeknownst to the mother at the time, her kid was also looking out for her.

“My daughter said she pushed the lady to defend me and the lady went under my arm and punched her in the mouth. Our faces were scratched, my daughter’s lip was swollen, and I had a lot of neck and back pain days after,” she explained.

The pair were taken to Jacobi Medical Center in stable condition, both with pain to their face and mouth.

The mom had a CAT scan at the hospital and “couldn’t work for two or three days because my head and neck were swollen,” she said, adding, “I could barely move for days, my body hurt.”

The suspect got off the train after the attack, cops said. 

Cops have released surveillance images of the heartless thug who went beserk.

The motive for the assault remained unclear Saturday.

The mom, who lives with her husband, son and daughter, was left on edge after the attack.

 “We’re both very scared to go on the train and are feeling scared in general,” she added.