Time is running out for people in low-lying parts of Westchester County who have been asked to evacuate their homes as Hurricane Sandy bears down on the East Coast.

Westchester County Executive Robert Astorino warned those residents Monday to leave their homes now, before conditions worsen this afternoon and evening.

“We’re not doing it just for the sake of doing it,” Astorino said of the local evacuations in flood prone areas of the county. “We are doing it because people and property are at risk.”

Speaking to reporters from the county’s emergency operations center in Hawthorne, Astorino said early this afternoon could be the last chance for these residents to leave areas that face the most dangerous flooding.

“Those who have not evacuated, if there are problems later, we may not be able to get to you,” Astorino said. “This is the perfect time still to evacuate.”

During a tour in the City of Rye and Mamaroneck earlier in the day, Astorino said he noticed several people out taking pictures; a practice he said will become increasingly dangerous throughout the day.

“It’s very important right now that people start heeding the warnings, stay inside, don’t go out and about,” Astorino said. “This is a serious storm.”

Although there were no incidents to report as of early Monday afternoon, Astorino said the county is prepared to help local communities if things worsen Monday evening. The National Guard has 100 drivers and 50 pieces of emergency equipment on standby at nearby Camp Smith. County workers will also be on call through the evening.

Mandatory evacuations to this point have been limited to localized and smaller areas. Astorino said it is unlikely more evacuations will be ordered Monday, as most residents will be urged to ride out the storm in the safety of their homes.

Hurricane Sandy has already caused significant flooding in parts of northern New Jersey and in some Sound Shore communities in New York. Heavy winds are expected Monday afternoon and evening and power outages could be a problem.

Astorino said county officials have been in contact with utility companies and that power will be restored as quickly as possible once conditions allow workers to operate in the area.

Bee Line Bus service has been cancelled as of Sunday night. Astorino said the service will likely not return until sometime Wednesday. The Bronx River Parkway will also remain closed Monday and probably Tuesday, Astorino said. Although Westchester County Airport remains open, Astorino said it is unlikely any flights will be coming in or out Monday or Tuesday.

It is likely the worse of the storm will hit the region Monday afternoon into early Tuesday morning, according to National Weather Service predictions. Astorino urged residents to keep in mind that the worst of the storm is still ahead.

“This is not an ordinary storm,” Astorino said. “This is a dangerous storm.”