The post reads, "If you can get to Manukau Bus Station asap free pies. Truck's door opened as he was turning the corner. Driver giving them away."
But a later comment said the pies were being loaded back into the crates, while workers in hi-visibility vests guarded them on the side of the road.
Don't worry team, staff are on the scene ensuring the safety of all pies caught up in the great pie spillage of Manukau. #keepyourpiesontheroad #safercommunitiestogether
Posted by Counties Manukau Police on Monday, 25 February 2019
Poster Toni-Marie Karaitiana said she didn't see the incident happen, but went past on the bus.
"I was sitting at the bus stop waiting for my mum when staff from Auckland Transport - ones that were helping - said to everyone come get free pies," she said.
In a statement, Big Ben said it was a "sad day for us at Big Ben pies".
"We've lost 4000 of our most delicious pies as they occupied Manukau Station Rd this morning.
"Please go out and buy a Big Ben pie for lunch in remembrance of the 4000 lost today," it joked.
"Their life (of pie) will be remembered in every bite of every future Big Ben pie. Our condolences are with the meat and pastry families. Rest assured we'll look after all the sausage rolls. R.I.PIE."
A Big Ben spokeswoman said the pies were being loaded into trucks to be taken away.
"From a food and physical safety perspective they can't give them away," she said.
Police received a report that a truck had spilled its load just before 9am today.
A number of pies were on the road and one lane was blocked as a result. Police assisted with traffic control at the scene.