The beleaguered cargo ship Rena, which ran aground on top of a reef off the coast of northern New Zealand, has split into two pieces, said media reports on Sunday.

Up to 300 containers were lost overboard after Rena broke up on Saturday night, officials told TVNZ.

When the ship got stuck atop the Astrolabe Reef in early October it had been carrying some 2,100 containers of a variety of products, according to insurer Gold Medal Insurance. Since then some had been removed in salvage efforts but about 840 were still on board when it split this weekend.

Adam Munro, a local cleanup official, said that a team is on standby to clean up and remove oil released by the ship over the weekend.

“Conditions are extremely changeable, but there is a possibility that debris and oil from the vessel might impact the eastern seaboard of the Coromandel Peninsula,” he told TVNZ.

“It was simply a matter of time before there would be a storm event of sufficient magnitude to break the vessel in two and what has transpired in the last 24 hours is very much expected,” Environment Minister Nick Smith told the New Zealand Herald newspaper.

Smith noted that the environmental hazard posed by the ship breaking up and casting off oil

containers into the ocean is much smaller than when it initially ran aground on the reef.

“It is possible that there will be releases of oil but they will be in the order of tens of tons and not hundreds of ton and those things are unlikely to result in any beach closures,” he said.