OTTAWA -- Police and health officials are warning the public about a string of overdoses in Ottawa, at least two of which were fatal.

City police say they encountered three separate incidents involving five people in a 14-hour stretch between Monday and Tuesday.

They say two of the overdoses were fatal, but did not provide further details.

Ottawa Public Health has issued an alert about the overdoses warning the public to be careful.

They say preliminary tests suggest fentanyl-laced cocaine may be the cause.

Police say they're investigating the situation.