COLUMBIA, Mo. (AP) – Police say a type of synthetic marijuana, possibly laced with dangerous narcotics or even rat poison, is to blame for more than dozen overdose cases in Columbia.

The police department said in a news release that five of the cases occurred between 5:30 and 6:30 p.m. Wednesday. Other overdoses were reported at extended stay motels. Police say no deaths have occurred.

The Columbia Tribune reports all the overdoses were linked to a synthetic marijuana commonly known as K2, which is sold under several names.

Police don’t know the source of the substance.

Earlier this year, a batch of K2 in the St. Louis area, which may have been laced with Fentanyl, caused several overdoses in one area in just a few hours.