Puerto Rico's governor warned congressional leaders over the weekend that the island is on the verge of simultaneous humanitarian and fiscal disasters in the wake of Hurricane Maria.

Gov. Ricardo Rossello told Speaker Paul Ryan and Senate Majority Leader Mitch McConnell in a letter that most businesses have shut down in the wake of the storm. He said that is putting the already fiscally shaky island under even more pressure.

"In addition to the physical destruction, Puerto Rico's economy has ground to a near standstill," Rossello wrote in his letter. He added that "very few businesses" are operating.

"Financial damages of this magnitude will subject Puerto Rico's central government, its instrumentalities, and municipal governments to unsustainable cash shortfalls," he said. "As a result, in addition to the immediate humanitarian crisis, Puerto Rico is on the brink of a massive liquidity crisis that will intensify in the immediate future."

Rossello asked Ryan, R-Wis., and McConnell, R-Ky., for another $4.6 billion to help the island, mostly in the form of more community block grants from the Department of Housing and Urban Development.

He said the storm has caused nearly $100 billion in damages.

"The unprecedented island-wide devastation in Puerto Rico has led to independent damage assessments in the range of $95 billion — approximately 150 percent of Puerto Rico's GNP," he wrote.