The mothers of Holly Wells and Jessica Chapman called police when they could wait no longer for news of the missing girls, the Old Bailey has heard.
Leslie and Sharon Chapman searched for the girls
Jessica's mother, Sharon, said she had looked at Nicola Wells and asked: "Do you want to do it or should I?"
In a statement read to the court she recalled her alarm at discovering her daughter's mobile phone was turned off.
She said she had worked every day with Ian Huntley's ex-girlfriend Maxine Carr, who Jessica considered "cool".
Mr Huntley denies murdering the girls, while Ms Carr denies attempting to pervert the course of justice and helping an offender.
Mrs Chapman's recollections of Sunday 4 August 2002, the day the girls went missing, were read to the jury on Monday.
They also heard from her husband, Leslie, Jessica's older sister, Rebecca, and Holly's parents, Kevin and Nicola.
Mrs Chapman described their day after returning from holiday in Minorca, during which Jessica was desperate to see Holly and they told their daughter to call and ask if she could visit.
The girls went missing during a barbecue at the Wells' home that evening and the families began a search for them.
Jessica had a mobile phone so she could always be in touch with her family, who were shocked to discover it had been turned off.
Mrs Chapman said: "Jessica would always take her mobile phone with her.
"I always knew where she was going and if she was going to leave that location, she would always ring me to ask if it was OK, for example to go to the sweet shop."
She said her daughter "would never switch her phone off".
Mrs Chapman said the decision to call police was made after the families' attempts to find the 10-year-old best friends failed.
She had gone to the Wells' house after checking the football club, the school field, the sports centre, the library and the school itself.
She said she and Mrs Wells had looked at one another, unable to bear what was happening and raised the question of calling police.
Mrs Chapman remembered saying: "I have only got my mobile, give me your phone."
The parents of Holly Wells described how they had not known Ian Huntley or Maxine Carr, but Mrs Chapman said they were familiar figures to her.
The learning skills assistant worked alongside teaching assistant Ms Carr at St Andrews primary.
She had spoken to Mr Huntley, the school caretaker, a number of times about things like the heating and toilets.
Mrs Chapman said her daughter thought a lot about Ms Carr and believed she was "cool".
Ms Carr had helped Jessica with coursework and homework and the 10-year-old was genuinely attached to her.
Jessica's mother said Ms Carr had mentioned to her that she was engaged to Huntley, but had
not spoken in detail about her past or personal life.
Mrs Chapman said she knew the younger woman had applied for a full-time post as a teaching assistant, but that she only discovered the application had been refused after Jessica went missing.