A steady stream of teenagers came by the Georgia Street home as word spread that members of the Tran family died in the overnight fire.
Trinh Tran, Tram Tran and a woman who friends say was their mother became trapped when the house broke out in flames.
"I wanted to come. Kind of like to pay my respects. I've always been there for them and they've always been here for me," said Gardenia Martinez, a friend of the twins.
The fire broke out at around 2:45 a.m. Sunday. The twins' 11-year-old sister managed to escape from a side window. She flagged down a police officer who happened to be driving by.
"At that point they made entry. They kicked one of the side doors, made entry but the house was fully engulfed and there was really nothing they could do at that point," said Lt. Jason Potts of the Vallejo Police Department.
Investigators won't say why but they believe the fire is suspicious, calling it an "active criminal investigation."
Trinh and Tram were going to be sophomores at Jesse Bethel High School. The two were in the school band. Trinh played the flute, Tram played the clarinet. They were also on a wrestling team while in middle school. That's where many of their friendships were made.
"They were really sweet to me. They always talked to me. One had a really fun attitude, the other was really loving and they were good girls," said Daniel Alencastro, a friend of the twins.
Friends of the surviving sibling also came to pay their respects. They say she was close to her older sisters.
"I'm really happy for her because she survived but I know she's going through a lot and I hope she's staying strong right now," said Marguerette Bui, a friend of the surviving sister.
Vallejo police plan to give updates on this case. They also ask anyone with information to call them.