AUBURN, Maine (AP) — Employees of a Maine restaurant got a surprise when they opened a large wooden crate that they thought was a shipment of mugs they had recently ordered.

Instead, they found a plastic tote that contained what law enforcement suspect is 14 kilograms (31 pounds) of the powerful synthetic opioid fentanyl with an estimated street value of $3 million, Auburn police Deputy Chief Timothy Cougle said in a statement Saturday.

The tote had a shipping label with the restaurant's address but the name of someone who did not work there. Employees who opened it saw what they thought looked like drugs, so they contacted police, Cougle said.

The crate from Arizona that arrived in the Maine town about 30 miles (50 kilometres) north of Portland was taken to the police department, where a chemical field examination confirmed it contained fentanyl.

About an hour later, the man whose name was on the shipment showed up looking for the crate and was arrested, police said.

Jeremy Mercier, 41, of Auburn, was charged with drug offenses and for violating bail conditions. He is being held in a county jail without bail. It could not be determined if he had an attorney.

Mercier previously spent time behind bars on a 2007 federal drug conviction, Cougle said.

The investigation is ongoing, and Cougle said he anticipates state and federal law enforcement getting involved.

Mike Peters, the co-owner of Mac's Grill, told WMTW-TV in an email that he is glad the drugs did not make it to the streets.

"The instances of overdose in our, and surrounding, communities is awful, and fentanyl seems to be front and centre when it comes to fatalities," he said. "It is very sad."