Furious residents of southeast Brooklyn vented their rage Monday as they waited for Con Edison to restore their electricity more than 18 hours after the power went out.

Dozens of people were lined up to get free dry ice from the back of a power company truck parked at Avenue K and 59th Street around 2:30 p.m.

“I don’t understand why it’s taking so long,” fumed Flatland resident Gary Headley, 62, a bus supervisor at La Guardia airport.

“Who knows when they’ll turn it on? They keep giving us different times.”

In Marine Park, retirees Barbara Riley and John O’Farrell held hands while trying to beat the heat on the porch of their sweltering home.

They said the lights began flickering around 6 p.m. Sunday, then went dark around 7 p.m.

“I just don’t understand why they didn’t tell anybody that they were planning to turn off the power,” said Riley, 78.

“They should have notified us in advance. It’s irresponsible.”

O’Farrell, 71, called the situation “crazy.”

“Whatever it is they were playing at, they messed it up. They only made things worse,” he said.

“I can only imagine the amount of food we are going to have to throw away.”

At a Carvel store in Marine Park, worker Chris Lopez, 20, said the lights started flickering around 4 p.m. Sunday and went dark at 6:30 p.m.

Lopez said he called Con Ed but was told the shop wasn’t a high priority.

“They basically told us to go f–k ourselves. Us and everyone on this block,” he said.

Workers sold items two-for-one before they resorted to just giving the treats away until the sun went down.

They then spent hours mopping up puddles of water and melted ice cream that dripped out of the freezers until 4 a.m., Lopez said.

Maria Notaro, owner of the Alliotta Pastry Shop in Flatlands, said she would have to throw out around $15,000 worth of baked goods, including three-tiered cakes, cream pies and eclairs.

“We are small business owners. It’s hard enough to pay the bills when things are going smoothly,” she lamented.

Store worker Josephine Francis was outraged that the traffic lights were working while the store remained blacked out.

“There’s electricity coming from somewhere. Why isn’t it here yet?” she said.

“Everything’s gone bad. Cookies are the only thing I could safely sell to someone.”

Next door, La Torre Pork Store co-owner Jose Ramos, 33, sat outside with two employees and said everything inside was now “garbage.”

“Chicken, beef, pork, cold cuts, sausages — beautiful meat,” he said.

“We can’t sell anything, I wouldn’t. We are just here waiting for the power to come back on so we can start throwing things away, cleaning up, and counting our losses. It’s going to be a lot of work.”

Con Ed asked customers in the area to begin conserving energy in a news release posted on its website at 5:15 p.m. and on Twitter about an hour later.