That day at school was very weird

When I was 7 years old I uses to go to a very old school. It had a weird schedule from 6am to 10am younger children used to stay and from 10 to 4 pm older children.

That day when school ended and I went outside my class to the school vans parked in the field outside none of my friends came with me. I thought I left too early but when I returned to the classroom it was empty then I heard prayers from the prayer hall I went inside and saw older children were praying. When I returned to the field where school vans were parked it was suddenly filled with children I went back to the prayer hall it was empty. I precisely remember that it was a Friday somewhere between may or June month in the year 2015.