Classmates of a murdered schoolboy yesterday paid tribute to their friend and his little brother who were found dead in a car at the weekend.

Children wrote messages on blue and yellow ribbons and tied them to railings bordering a garden of remembrance in the playground of Royston Primary School, Glasgow, where Paul Ross, six, was a pupil.

A pear tree was planted in the garden for Paul, next to a tree planted four years ago in memory of Mark Cummings, another former pupil at the school, who was murdered by known sex offender Stuart Leggate in 2004.

Paul and his two-year-old brother Jay died what is believed to have been violent deaths and were found in a car parked on the Crow Road near Lennoxtown on Saturday. The boys' father, Ashok Kalyanjee, is in a critical condition in hospital in Glasgow, were he was placed under police guard following the deaths.

Dozens of parents turned up to pay their respects at the service, which was led by the former school chaplain, Russell McLarty.

The children sang Kumbaya My Lord and Over My Head I Hear Music in the Air. Headteacher Liz Davidson spoke about the little boy, whom she earlier called "sweet, smart and adorable". Following the service, the entire school walked to the garden and tied their ribbons to the railings.

Among the messages were "We're thinking about you" and "I'll never forget you". Each class also placed an ornamental butterfly around the tree, beside single roses left on the ground.

One message from Paul's class teacher said: "We will miss you but will never forget the happy times in Primary Two - Mr Flanagan."

For the wider community of Royston, it was the second time a service had been held at the school for a pupil who suffered a tragic and violent death. Some, in tears, hugged at the school gates as the children returned to classes.

Mark Cummings's grandmother attended the service to support her other two grandsons, who are pupils at the school. Mark was eight when he was assaulted, killed and thrown down a rubbish chute by Leggate, who lived in the same tower block as the boy.

Leggate was jailed for life in 2004 and ordered to serve a minimum of 20 years before seeking parole for the murder.

Isabel Cummings said: "It brought back a lot of memories. I have two grandsons at the school, and the community has been great, just as they were when Mark died."

Mrs Cummings was accompanied at the service by friend, Catherine McKenna, who said: "I really felt for the kids. We all know the boys' mum, Giselle, and their dad because he worked in the post office."

Mr McLarty, now in a post in Edinburgh, returned to the school where he was chaplain at the time of Mark's death to help the staff and pupils.

He said: "Some children will show their tears, while others are deeper. We wanted to allow them to express their feelings in different ways with songs and prayer and the messages on ribbons.

"The teachers at the school knew Paul and Jay very well and both parents. There is a deep sense of grief and loss."