The number of COVID-19 cases in Darien shot up in the past 10 days, a group of town officials, including health officials and school officials, said in a letter to town residents released Tuesday afternoon (full text below). The officials asked residents to be sure to follow health guidelines, although school children have been getting only “mild” cases. “In the past 10 days we have seen a surge in COVID cases across the school district, especially in our elementary school population. Fortunately, the level of illness of the individual positive cases continues to be mild. Increases in COVID cases have also been reported in the town,” the letter said.