The schools included Delhi Public School, Modern Convent School, and Shree Ram World School, a senior police officer said, adding that the threats were received via e-mail.
Kaamya Karthikeyan, a Class 12 student, is the youngest woman in the world to scale the seven highest peaks across seven continents.
Kaamya Karthikeyan, a student of Navy Children School, Mumbai, and daughter of a Naval officer, attained the summit of her second 'above 6,000 m' peak, Mt Mentok Kangri II, 6,262 meters (20,544 feet), overlooking the Tso Moriri lake in Ladakh on August 24.