Rafiq Maliha, the director of the electricity company, told Al Jazeera on Saturday that no fuel had been delivered since Thursday and that they would be "forced to shut down the whole plant on Sunday" if fuel was not allowed in.
While Israel's announcement of the re-opening of the crossing came quickly after the power was cut on Friday night, the electricity outage for thousands of Palestinian homes highlighted how reliant the territory is on its neighbour.
Maliha said that the shut down of three generators had "completely stopped" the Gaza Strip's infrastructure.
"Simply, if you have no electricity, you have no water, no services, no hospitals. This would be a terrible situation for the people here.
"The power plant has only been producing a 25-megawatt supply from the 140-megawatt desired capacity of the power plant."
Palestinian officials said at least 600,000 of Gaza's 1.4 million people were affected by a blackout on Friday, which brought darkness to large areas of the territory.
The Palestinian electricity company's one power plant produces three quarters of the electricity needed by the territory, but Israel supplies it with the fuel as part of past interim peace deals.
The remaining electricity needs are from the state-run Israel Electric Corporation and Egypt.
Almost all supplies for Gaza, including food, fuel and raw materials, come into the territory from Israel.
Israel started to cut off supplies to Gaza after Hamas took full control in June, citing "security concerns" in opening border crossings.