Seventy-two people in New Haven, Connecticut were hospitalized on Wednesday after suffering from an overdose caused by synthetic marijuana. According to NBC, some locals suffered from life-threatening symptoms and were unconscious, but so far no deaths related to the overdoses have been reported.

The outbreak is believed to have been caused by K2, and began on Tuesday evening. Three people overdosed near Yale University, and Wednesday morning 18 more collapsed in a park near downtown New Haven. Within 24 hours of the first overdose, there were 76 reported cases.

The Drug Enforcement Administration ran tests of the drugs used by some of the victims, and revealed K2 was laced in the marijuana, but other victims had traces of the opioid fentanyl in their system and were treated with naloxone.

“I’m extremely grateful for the timely and effective work of first responders who helped revive, transport, and save these victims,” New Haven Mayor Toni Harp said in a statement.

This mass overdose is just one of several incidents to take place this year. Back in May, 25 people in Brooklyn were hospitalized after using K2, and one man in Illinois died, while 38 others overdosed, after consuming the synthetic cannabinoid in April.

K2 is a synthetic compound that mimics THC, but is more dangerous because of the mishmash of chemicals and wide variety of doses used to create it. After consuming it, people can suffer from psychosis, seizures, breathing and circulation problems, comas, and sometimes death, especially when it's laced with other drugs like fentanyl.

So far, local police have arrested one person in connection to the overdoses.