JAMAICA, Queens (WABC) -- Parents rallied Friday at City Hall, taking aim at violence in schools.The Families for Excellent Schools group said the presence of weapons in schools has risen 25 percent and it is criticizing Mayor Bill de Blasio for lack of action to protect students.The group quoted New York City Police Department data that said the number of guns and the number of knives found in schools went up 30 percent each; the number of stun guns went up more than 1,000 percent.The Department of Education responded Friday morning by insisting that "there is absolutely zero tolerance for any weapons in schools." The department said it works closely with police to ensure the safety of all school communities.This week, there have been two separate incidents of students bringing loaded guns to schools. On Thursday, a student at a public school in Jamaica, Queens, was found with a gun.Authorities said a 15-year-old at the York Early College Academy on 167th Street was caught with the weapon after another student overheard talk that the firearm was in his possession. A .38-caliber revolver was recovered from his backpack.Charges against him are pending. There are no metal detectors at the school.The Department of Education released the following statement:"This is deeply alarming, and we are working closely with NYPD to ensure that all students and staff are safe. The police department immediately responded and are investigating the troubling incident. We are providing additional resources to support the school community and families were notified."On Tuesday, 56-year-old Kenneth Miley was arrested after his 11-year-old grandchild was found with a loaded gun inside PS 40 in South Jamaica Authorities said that student had gotten into a fight with another student on Monday, and a day later, the gun was found in his backpack. Miley was charged with criminal possession of a weapon, endangering the welfare of a child, and reckless endangerment.Parents who were leaving the building Thursday said they had no idea a student had brought the weapon to school, and upon seeing the picture, they were horrified."I never heard anything like this before," parent Shalda Mitchell said. "Nothing. I'm shocked. Wow.""I think that's dangerous," parent Willie Wright added. "That's a serious thing. Whoever the parent is, they really have to take some responsibility."