Yes!
My exH done exactly what you said, he took the children from school and I didn't see them for three weeks! Despite going to school, his work, social services. I couldn't get access he claimed I had mental health issues and couldn't be trusted with the children. Because he was on the birth certificate and he had 50% rights and his care was deemed 'safe'.
I was in the care of Harbour at the time (uk). This is to help with domestic abuse, they hired a solicitor for me and we started court proceedings straight away. I had to prove I was mentally able to look after myself and my children. I went to therapy and attended multiple sessions as evidence for court. I also had police assessing my property, making sure it was a safe, clean home, they had a suitable bedroom and food in cupboards. I was mortified! After all this evidence had been provided the children had to be interviewed by CAFCAS to have their own voice in court.
Social services also provided reports. In these reports I learnt he had been abusing the children in his own home, his neighbours had reported him for months and I had no knowledge of it. It was down as suspected child l abuse. I was disgusted that social services seemed to have these reports yet didn't do anything about them but managed to support his decision to keep the children from me. The children came back into my care within the month. They spoke about how exH would pin them and hit them, police and social services interviewed them. My 4 year old son laid on the ground and acted the abuse out, then used his own figures to show the abuse. Nothing happened from this as it wasn't enough criminal evidence. They said they couldn't trust the word of a 4 and 2 year old, even with the other reports backing them? I was said in court he could have access through contact centres as it would be supervised. I spoke with my solicitor and we denied the contact visits. They came to the door weekly to collect the children and I would turn them away, they tried to tell me it would go against me but I still continued fighting for the children. I kept them from school until the school would apologise for refusing my access to the children and guarantee he could not come to collect them.
I felt the children were unsafe. After over a year in courts we got the final order. I got full custody and he got no contact, he gets to write to the children once a month, no more than that. It was finalised as 'over chastisement of the children' which dumbs down to inappropriate punishment of our children. I was sickened. He was so good at painting the innocent party. I was angry at the system allowing him to take my children away and them being in his care for a period of time suffering.
My son is now 8 and is underweight, he does to counselling and play therapy within school. He is behind in work and struggles to verbally communicate. I am saddened that this is the long term affects from both their biological father and the system that should protect children. It makes me so angry!!
My daughter is now 6 and doesn't remember anything, she is a bubbly little girl and I am glad I got to save her from it although the guilt racks up when I think of my boy.
I have since moved towns and refused to pass on any information. I have deleted social media and will not allow him to have a glimpse of the children that he should have loved!!