San Juan, Sep 28 (IANS): About 97 per cent of Puerto Rico's 3.4 million residents were still without electricity, one week after Hurricane Maria slammed into the US territory, Governor Ricardo Rossello said.

About half the residents do not have running water and authorities were working to get food, fuel and water "everywhere on the island", CNN quoted Rosello as saying on Wednesday.

Puerto Ricans were waiting hours in line to get gas, food and cash. Gas stations and supermarkets are rationing supplies, while banks are running low on cash.

"Right now we are in emergency mode... Our focus is not necessarily restoring energy. The energy grid has been destroyed... And we need to rebuild it. That does not get rebuilt in days," the governor said.

He said getting aid where it was needed has been a challenge because of the magnitude of the destruction on the island.

"This has been the biggest catastrophe in the history Puerto Rico in terms of natural disasters."

The hurricane that made landfall earlier this month killed 16 people in Puerto Rico, 27 in the island nation of Dominica and one in the US Virgin Islands, CNN reported.

On Wednesday, a plane carrying 3,500 pounds of water, Army meals ready-to-eat, diapers and other supplies headed from Florida to Puerto Rico.

The plane returned to the US mainland with dozens of family members of federal employees.

Two military officials told CNN that another 2,000 to 3,000 US troops will be sent to Puerto Rico in the coming days to assist with aid.