Middlesex Borough police are investigating after thieves made off with a Costco-bound tractor-trailer and more than $300,000 worth of seafood inside early last week.

“It's a bit unusual. Very high dollar amount, obviously,” said Detective Sgt. Sean Flanagan, from the Middlesex Borough Police.

The tractor-trailer is valued at $50,000. It was carrying an estimated $305,000 worth of seafood.

Police said the goods were set to be delivered to Costco in Monroe. The victim was renting a parking space on Smalley Avenue.

“It was actually the owner of the truck that reported it,” Flanagan said. “He came back and saw that it was stolen. There were four other cargo containers that were opened. Nothing was taken.”

Police said they’ve received surveillance video from the public, but as the investigation continues, some details are still murky.

“It's on private property, in a fenced-in lot,” Flanagan said. “We have different theories and leads right now. We can't say for sure how they knew it was there.”

Despite how fluky this crime seems, police said local car burglaries are on the rise.

“If they do see a key fob, sometimes it's a crime of opportunity; they'll steal the car,” Flanagan said. “But if not, they're looking for quick items - cash, loose change, cellphones, purses. The past few weeks, it's been the east side of our town towards Dunellen.”

Police say nearly all of the car thefts involve unlocked cars.