(CNN) – A video shows a pregnant woman being attacked by two teenagers in Massachusetts.

In the video, the victim, who is 5-months pregnant, can be heard screaming as her boyfriend steps in to defend her.

Moments later, an elderly man in a red hat tries to help keep her attackers away.

The victim reportedly told police one of the suspects said “I hope he dies. I will kill your kid.”

Alec Zeng saw it all unfolding as he was leaving the post office in Quincy on Tuesday. He quickly turned on his phone’s camera to help police by capturing part of the attack.

Zeng called 911 and followed the suspects, then police arrested them just a few blocks away.

The pregnant victim later told police she had been throwing up earlier when the suspects walking by started to laugh at her.

She said one of them spit on her and her boyfriend, then the pair started punching her in the head.

Tyrese Johnson-Nurse, 19, and David Russell, 18 are facing charges for assault and battery on a pregnant woman.

The woman did not have any visible injuries but did go to the hospital to check on the health of the baby.

Johnson-Nurse and Russell are due in court in May.