(WHTM) — Ahead of Halloween, the Drug Enforcement Administration is doubling down on its warning about so-called “rainbow fentanyl,” which looks like candy and is made to appeal to a younger crowd.

Agents in New York announced this week they seized 15,000 multi-colored fentanyl pills hidden inside a yellow Lego box. It’s the largest bust of fentanyl pills in the city, worth $300,000.

The DEA says rainbow fentanyl comes in a variety of bright colors, shapes, and sizes. Authorities are calling it a newly packaged poison. It’s not just pills, but also powders and blocks that resemble sidewalk chalk. In August alone, rainbow fentanyl was seized in 18 separate states.

The DEA says the new packaging is a deliberate effort by drug traffickers to drive addiction in kids and young adults. Fentanyl, a powerful synthetic opioid, is believed to be 50 times more potent than morphine.

Recent data shows a 40% increase in the number of deaths among teenagers and young adults due to fentanyl.