In a crackdown on the e-cigarette industry, the FDA has issued warning letters to dozens of retailers that violated new rules by selling e-cigarettes, hookah tobacco and other tobacco products to minors.

The retailers included some specialty stores, online establishments and major national chains, including 7-Eleven, Chevron and Walgreens, the administration announced Thursday.

Officials discovered 55 retailers where minors were able to purchase some tobacco products, such as e-cigarettes, cigars, hookah and pipes. Some of the products included “youth-appealing” flavors, the administration said, such as e-cigarette liquids flavored “Cap-N-Crunch Berries” and “Strawberry Cake Pop.”

The warning letters went out about one month after the FDA banned the sale of all tobacco products, including e-cigarettes, to anyone under 18. The administration also required retailers to check the photo IDs of all tobacco customers under 27.