MERRICK, N.Y. (CBSNewYork) — One Long Island teenager is the hero of her family after she knew exactly what do do when her grandmother suddenly collapsed.

The two have always been close. Now they’re closer than ever after the quick-thinking high school senior saved her grandmother’s life.

“I know that when people say that ‘oh, I love my grandma,’ like, they take for granted that she’s actually here,” 17-year-old Zarah Ibrahim tells CBS2’s Hazel Sanchez.

It happened right before a girls basketball game inside the gym at Calhoun High School in Merrick. Zarah’s parents, sister, aunt, and 78-year-old grandmother, Graciela Perlaza, were there.

It was the championship game for the North Bellmore/North Merrick basketball league. Zarah was getting ready to run the scoreboard when she noticed her family panicking on the other side of the court.

Her grandmother had collapsed and was unconscious.

“It was really, really scary,” Zarah said. She said she feared her grandmother was gone when she didn’t feel a pulse.

A competitive swimmer and life guard, Zarah was certified in CPR — so she did what she had been trained to do since the eighth grade. But first, she said she panicked.

“My dad had to not like, yell at me but like, yell at me and tell me ‘you can’t panic in this type of situation’,” she said. “He’s like ‘do it, do it,’ so then I was like ‘okay, I’ll do it,’ and I started doing compressions for less than a minute and then my grandmother was like ‘ow, stop!’ and she was revived.”

Zarah said she was overwhelmingly relieved to see her grandmother breathing and alert.

“I literally just grabbed her hand and just sat there,” she said. “You never know. If I wasn’t certified or no one else was certified I don’t know if she’d be here. So I don’t take it for granted, seeing her.”

Doctors are still trying to figure out what caused Perlaza to collapse. Her family tells CBS2 she’s at home recovering and her granddaughter, bound for UConn to study law in the fall, says med school might not be out of the question.

Watch & Listen LIVE