It must be handled immediately by parents or it will continue. If the fires are small, there is not big deal. Anytime children set fires, they are endangering themselves and others. Telling a young child not to play with matches and lighters should be all that is necessary. Only boys play with matches.
Children learn from their role models, set good examples of fire safe behavior.
Keep matches and lighters out of children's reach. Teach your children to tell an adult if they find matches or lighters. When your children express an interest in matches or lighters, teach them that they are tools not toys, and when age appropriate, explain about holding matches and lighters away from the body and striking a match away from your body. Under direct adult supervision, parents may feel the time is right to allow a child the opportunity to light the match or lighter, i.e., lighting a candle or fireplace fire. Watch for telltale signs of fireplay experimentation.