This National Oceanic and Atmospheric Administration satellite image, taken and released on August 27, 2011, shows Hurricane Irene after it made landfall along the US Atlantic coastline. [China Daily via Agencies]

U.S. government officials warned on Saturday that Hurricane Irene, although a little weakened after it slammed the shores of North Carolina, remained "dangerous" and residents on the East Coast have to take it seriously and get prepared.

The warning was issued at a joint press conference held by Secretary of the Department of Homeland Security Janet Napolitano, Federal Emergency Management Agency (FEMA) Craig Fugate and National Hurricane Center Director Bill Read.

Napolitano said Hurricane Irene remained a "large and dangerous " storm as it was advancing up the East Coast, and the residents living on the projected path of the storm have to get prepared by stocking up on drinking water, food and other emergency supplies.

People could still anticipate heavy rain, potential flooding and significant power outages along the eastern seaboard, she added.

For his part, Read said he expected that the beach resorts along the coast of New Jersey would be affected by the storm on Sunday morning and a storm surge was forecast for Long Island Sound and New York City.

FEMA will start response phase in North Carolina as Irene moves north, Fugate said, while urging people to "stay inside."

U.S. President Barack Obama, who cut his vacation short and returned to the White House Friday night, convened a conference call with federal emergency officials Saturday morning, the White House said in a statement.

Napolitano and Fugate updated the president "on the intensity of the storm, the anticipated track of the storm and the response and recovery assets that have been pre-deployed along the east coast in anticipation of the storm's arrival," the statement said.

"The president reiterated that we know that this storm's impacts will continue to be felt throughout the weekend and that we still have work ahead of us to support potentially impacted states and communities," it said.