Originally Published: 03 SEP 21 01:25 ET

Updated: 03 SEP 21 13:23 ET

By Madeline Holcombe and Jason Hanna, CNN

(CNN) -- After Ida's remnants swept through the East Coast and left at least 48 people dead, New York's mayor said the extreme rainfall should get everyone "to act very differently" -- including expanding expectations for evacuations.

"This is a new world," Mayor Bill de Blasio told CNN Friday, arguing that the intensity and frequency of storms are rising through climate change and saying the US is going to need "entirely different responses."

With this storm causing so much flash flooding inland, he said he would consider being more aggressive in the future with pre-storm evacuations and orders to clear streets and subways -- steps he said he'd normally reserve for hurricanes or massive blizzards.

Later Friday, he said a new city task force would determine protocols on when and how to clear the streets and evacuate ahead of storms.

"We're going to have to be much more aggressive with these tools," de Blasio told CNN Friday.

The storm -- by then remnants of a tropical depression -- unleashed deadly flooding Wednesday from Virginia to New England, but especially from metro Philadelphia to New Jersey and southern New York. That came after Ida devastated parts of the Gulf Coast as a major hurricane Sunday.

Of the dozens killed in the East, many died in flooded homes -- including many in flooded basements -- or while overtaken by water in or outside their vehicles.

At least 25 died in New Jersey and 16 died in New York state alone. President Joe Biden has approved an emergency declaration for those two states, the White House said late Thursday.

Four deaths also were attributed to the storm in Pennsylvania, and one each in Maryland, Connecticut and Virginia.

As for what to expect with any new policies, de Blasio said Friday these could include sending cellphone alerts to people living in basement apartment ahead of storms. He did not say how soon policies would be established.

Friday morning, about 4.5 million people in the Northeast remained under flood warnings, mostly in northeastern New Jersey, as rainwater flows into larger creeks, streams, and rivers. Some rivers in the Northeast are forecast to remain above flood stage into the weekend, though many are already receding.

"We have to start from scratch as we are mourning," Amrita Bhagwandin of Queens, New York, told CNN's Chris Cuomo on Thursday. "We have to see how we can move on in the most graceful way here. Because this -- if you see the situation here, it's very unsafe, very unlivable. Death is upon us."

Bhagwandin's home sustained serious damage in the flood, but her biggest heartbreak was losing her neighbors, a mother and a son, she said.

Bhagwandin's husband, Sahadeo, said that their neighborhood has had flooding issues before. And officials may come through during times of disaster, but the residents there need more action.

"We need a lot of help in this neighborhood and over the years we have been neglected. I came here in 2003, and since 2003 to 2021, we're getting flooding and nothing has been done," Sahadeo Bhagwandin said. "We have several projects that were completed in this block but it is not resolving the issue we have."

New York Gov. Kathy Hochul said she wants answers.

"I want to know who knew what when and what could have been done differently -- because New Yorkers deserve to know what we're doing to learn from this event and make sure that it doesn't happen again," Hochul told CNN's Anderson Cooper on Thursday.

But part of making sure it doesn't happen again is fighting back against climate change, Hochul said. She advocated for a continued transition in the state to carbon neutral energy.

"We have no choice my friends, the future we spoke about in dire terms, that future is now. It's happening, we're losing life, lives we're losing property and we cannot continue on this path."

Officials have said the death toll could rise. Six people were missing in New Jersey on Friday morning in connection with the storm, the governor's office told CNN.

25 homes destroyed or damaged by tornado in New Jersey

At least eight tornadoes were confirmed in the Northeast on Wednesday: four in Pennsylvania, three in New Jersey and one in southeast Massachusetts, according to the National Weather Service.

In the southern New Jersey community of Mullica Hill, a tornado destroyed or severely damaged 25 homes, police Lt. David Marrow said. The weather service rated that tornado an EF-3 with 150 mph winds.

Hundreds of trees were downed, and power was knocked out for a third of the township, Marrow said.

"This is going to take some time to dig out of, there's no question about it," Gov. Phil Murphy said Thursday, standing in front of one of the wrecked homes.

As terrifying as the tornadoes were, none of the state's storm deaths were related to them, Murphy said, adding that he believes residents took the flood warnings less seriously than the tornado warnings.

"The tornado warnings came out just as the flood warnings came out," Murphy said. "Everybody, when they got the tornado warning, went into their basement and I think there were too many people who thought that they could deal with flooding and sadly, some of them either in their homes or in their cars, lost their lives."

People standing to ensure they did not drown in the bus

The danger of floodwaters was readily apparent in New York City, where the police department made 69 water rescues and 166 non-water rescues, Police Chief Rodney Harrison said.

More than 800 subway riders were evacuated, Harrison said Thursday. And another 500 New Yorkers were rescued from flooded roadways, buildings and subway stations, the New York City Emergency Management Department said.

In the chaos, New York bus driver Rosa Amonte became an overnight viral sensation after she drove passengers to safety, even as 3 to 4 feet of water filled the bus.

"People literally standing on their seat to make sure they did not drown inside a bus," Hochul said. "She stood there, she drove, through the night and did what it took to get people there safely."