Montreal public health says it's investigating a series of overdoses in downtown Montreal that sent six people to hospital yesterday. In a statement, public health said the situation is extremely concerning, but that it's not the first time that a similar situation has taken place due to contamination of street drugs with synthetic opiates, such as fentanyl, and other potent medications.An ambulance is seen in Montreal, Wednesday, January 29, 2020.THE CANADIAN PRESS/Ryan Remiorz