South Wales Police investigating those responsible for the outbreak of grass fires which have blight Valleys communities over the last month say they made eleven arrests of both children and adults over the last 24 hours.
Assistant Chief Constable Richard Lewis said there was also "four voluntary attendances" by people at local police stations.
The force has pledged to crackdown hard on those responsible and assisting those starting the fires.
The maximum penalty for starting fires is two years in prison and/or a £500 fine.
On Wednesday there were huge mountain fires around Wattsville near Crosskeys which required a helicopter carrying water to helping firefighters tackle the blaze.
South Wales Fire Service said it was started deliberately, affecting over 700 acres - making it the biggest such fire this year.
South Wales Police says more arrests are likely as they are receiving unprecedented amounts of community information.
Parents are being urged to be vigilant for the signs of firesetting and have issued signs to be on the lookout for:
Look out for small burn holes in carpets, charred paper in sinks or wastebaskets.
Matches and lighters may be hidden in their cupboards, drawers, under bed, school bags
They may know exactly where to get yours from even if you think you have hidden them
They may come home from playing out smelling of smoke
Your child may express a fascination with fire
You have an unexplained fire in the home
If you suspect your child is playing with fire:
Act straight away, you could reduce the chances of your child starting a fire.
Consider you own actions and how they might influence the behaviour of the children
If you think the problem is serious or you feel you need help to deal with it then you can call the Fire Service’s Firesetter intervention scheme - call 0370 6060699 or visit the website www.mawwfire.gov.uk