Pictures were posted on social media of the trophy, also known as the 'log o' wood', broken in two, with a caption reading "f**k we broke the ranfurly".
On one half of the trophy appears to be white powder, including some chopped up into lines, along with a rolled up piece of paper.
The destruction of the shield occurred during celebrations on Saturday night, after the Hawke's Bay Magpies claimed the trophy with a 20-18 win over holders Wellington Lions.
Hawke's Bay Rugby Union chief executive Jay Campbell said the trophy was accidentally broken when it was dropped onto a concrete floor.
"No one is more disappointed than Hawke's Bay Rugby and those involved," Mr Campbell is quoted by Radio NZ as saying.
"For us to be the cause of damage to something that's so unique and special to New Zealand rugby is devastating.
"It was an absolute accident."
New Zealand Rugby (NZR) had just replaced the old trophy - which was in service for 108 years - with a new one, made from English oak taken from Wellington's Hutt Valley, like the original.
The Ranfurly Shield is a challenge competition fought over by New Zealand's provincial rugby unions since 1904.
Once a team has taken possession of the log o' wood, it must be won off them in a match in their home province.
Wellington - who won the trophy last year off Hawke's Bay - had held possession for seven challenges, the most successful run in the history of the Ranfurly Shield.
NZR executive Steve Lancaster said the governing body was "deeply disappointed".
"NZR will now take possession of the shield, begin the process of repair and reassess the protocols in place to look after it," he said.
"Our intention is that the Ranfurly Shield remains a part of the community, is enjoyed by those who hold it and cared for as a taonga (treasure) of our game."
Broadcaster Scotty Stevenson fumed at the debacle in an emotional piece written for TVNZ.
"Many of the greatest players in this nation's provincial rugby history spent years trying to win that hunk of lumber. Many never did," he said.
"To watch it seemingly treated like some throw-away prop at a B-grade party actually hurts."
