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The woman – who did not want to be identified – told 10News, "There were a lot of people killed. It was my son, my father and three more."

Her son, 13-year-old Ulysses Castrejon was killed execution-style last month along with his grandfather.

"They took the only thing that I love," said the woman.

Martha Lizeth Osegueda Rodríguez, Erick Arzáte García and Marco Antonio López Carmona were arrested on Friday in connection with the massacre.

Osegueda is believed to have been a drug dealer out for revenge.

"I don't know why this happened to us because we were a family… a happy family," said the woman.

In January, the family went to Tijuana to celebrate Ulysses' 7-year-old cousin's birthday. She said they did not know many people at the party or even the homeowner.

"I was taking pictures [of] my son because he was laughing and playing with the cake," she said.

The laughter turned to terror when she said three men – wearing black masks with big guns – burst into the home.

The women and children were ordered into one room and Ulysses went with the men.

"And then I heard the shots and I [went] outside and I saw all these people killed and there was my father and my son," she said.

Although three people have been arrested, the woman believes two others may have played a role that night.