A murder jury was read a statement on behalf of Sara Broadhead in which she described waking in the middle of the night and her home filling with fumes and smoke.
Leeds Crown Court has heard how Andrew Broadhead, 42, and daughter Kiera died during the incident at their home on Ash Crescent, Stanley, Wakefield.
Mrs Broadhead, 35, and elder daughter Mia, 13, survived after being helped to escape the blaze by neighbours.
In a statement read by prosecutor Jonathan Sharp, Mrs Broadhead described being awoken by a loud bang as she was in bed with her husband in the early hours October 19 last year.
Mrs Broadhead said she looked over the bannister and saw flames surrounding the front door.
She said: "I started shouting 'fire, fire, we need to get out.'
"Andy and I were in a panic, bumping into each other on the landing."
Mrs Broadhead described how she went to Mia's bedroom and told her to climb out of the window while her husband went to get Kiera.
Mrs Broadhead and Mia then climbed out on to the roof of a utility room.
She said: "I could hear Andy coughing and Kiera screaming but when I dropped down onto the flat roof they weren't behind me."
The statement continued: "It all went quiet and I just knew."
Jurors were also told how Mrs Broadhead's worst fears were confirmed when emergency services arrived.
The statement continued: "The fire brigade came and they managed to get inside. Eventually I saw Kiera being carried out and as they were bringing her down I saw her arm move and my heart jumped.
"She was laid on the grass but then I realised that she hadn't made it.
"I was standing there in a daze staring at my little girl on the grass."
Daniel Jones, of Spawd Bone Lane, Knottingley, pleads not guilty to two charges of murder and two alternative counts of manslaughter.
He also denies arson with intent to endanger life and an alternative charge of arson being reckless as to whether life was endangered.
Jones also pleads not guilty to burglary.
The prosecution claims Jones poured petrol through the letter box of the property in order to destroy possible CCTV evidence of a burglary he is alleged to have committed days earlier at another house in the street.
Mrs Broadhead said in the statement that the CCTV camera on the front of the house was not working at the time of the incident.
The trial continues.