Headteacher Sandrina Lawson said: "The main thing is that everyone is safe. Staff are devastated at the loss of valuable resources.
"We have been working hard over the summer to prepare for our move to our new school.
"To lose years and years of children's and teachers work is extremely upsetting. Many members of the local community are also upset at seeing the damage caused by the fire."
Residents living in homes near the school, in the town's Highstonehall Road, raised the alarm at around 10pm last night.
Three fire crews spent the night dousing the flames, which could be seen for miles around.
A high-reach appliance was still pouring water onto the blaze at 7am this morning.
Around 90 pupils attend the Catholic primary school, which operates well below its 270 capacity. The school shares a site with St Peter's Primary, which looks to have been largely unaffected by the fire.
Six teaching staff at Our Lady and St Anne's were due to go back to work on Thursday ahead of kids returning to class next Monday, but education chiefs will now have to make urgent alternative plans.
Police cars stood guard outside the school today while firefighters secured the area.
None of the neighbouring homes was affected by the blaze.
A Strathclyde Fire & Rescue spokeswoman said:
"Three fire crews were at the scene through the night.
The situation is ongoing."
Strathclyde Police said an inquiry had been launched but it was too early to determine the cause of the blaze.
South Lanarkshire Council's education department staff were due to visit the site today to determine the extent of the damage.
jonathan. paisley@ eveningtimes. co. uk
Originally published by Newsquest Media Group.
(c) 2008 Evening Times; Glasgow (UK). Provided by ProQuest Information and Learning. All rights Reserved.
Written by Johathan Paisley