Environmental officials are investigating a massive fish kill on Long Island in which tens of thousands of dead fish turned up in a canal Monday.

The New York Department of Environmental Conservation said the Shinnecock Canal in Hampton Bays was closed at 3 am EST, trapping a large and dense school of Atlantic menhaden (bunker) fish.

The DEC said it believes the fish died due to a lack of oxygen and a high density of fish in the water.

The DEC said once the Suffolk County Department of Public Works opened the canal locks at 10 am EST, a lot of the fish washed downstream -- some of them still alive.

"The large school of fish was most likely chased into the canal by other predatory fish," the DEC said in a statement.

According to the Westhampton Patch, the fish kill drew crowds and traffic to Hampton Bays Monday as stunned spectators lined the bridge to witness the piles of dead fish.

"Everyone has the same, sad look on their face," said Bob Walsh.

"There are hundreds of thousands, if not a million, dead bunker," Southampton Town Supervisor Jay Schneiderman told the Patch.

"We fear it's going to get worse tonight, because there are a lot of live bunker still in the Shinnecock Bay. They're going to run out of oxygen. There's just not enough of a water column, when you have that many fish in a small, concentrated area," Schneiderman said.

Some, Schneiderman said, have estimated that there are possibly two feet of dead fish and possibly more at the bottom, the supervisor said.

Schneiderman said he's been working with the New York State Department of Environmental Conservation to come up with a plan.

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