A teenage girl in foster care set fire to her bedroom while two people were in the house, a court heard.
Leighla Long barricaded herself in the bedroom using furniture, but climbed out of the window.
Two police officers risked their lives kicking in the bedroom door, thinking she was trapped inside.
Long, 18, was sentenced to two years detention at Leicester Crown Court yesterday.
She admitted arson at the house in Town End, Hungarton, being reckless as to whether the lives of the foster carer and her 18-year-old son would be endangered on June 4.
Victoria Rose, prosecuting, said the house was badly damaged upstairs. Flames also spread through the loft to next door.
Long, who was 17 at the time, was behaving normally earlier that day.
Miss Rose said: "The foster carer then heard some banging and found the defendant on the conservatory roof.
"She told her to come down and went to call the police.
"The defendant went to her bedroom and pushed a chest of drawers across the door.
"The carer then saw smoke coming from under the door."
She and her son safely left the property.
Police officers, who arrived first, kicked open the defendant's bedroom door to find Long was gone.
Miss Rose said: "The fire was extensive with heavy smoke and teams of fire fighters were using breathing apparatus."
Three appliances and a support unit attended, along with 15 firefighters.
The fire was started deliberately by the defendant, but no accelerant was used.
The next door house was due to be sold, but had to come off the market because of the damage.
In interview, Long claimed she went on to the roof to self-harm and, after starting the fire, "forgot" about it.
Sentencing, Judge Michael Pert QC said: "You caused a considerable amount of damage.
"People didn't know you weren't in the building and two police officers made their way in to a burning house in an effort to save your life."
Harry Bowyer, mitigating, said: "She's had a very troubled upbringing.
"Her family are still in contact with her and sit in court today. She was unwell and unhappy at the time.
"She has since made progress while on remand in custody and is a much less angry person today.
"She wants to apologise to her foster carer and is well aware of the grief she's put her and the next door neighbour through."
