It's all because a levee broke in Windsor, sending water into the Raritan Canal, causing it to overflow.
Officials say there are cars submerged in 12 feet in water in some areas, with some houses being partially washed away.
One of the homes belonged to Brenda Cambrara. She was among those who evacuated on Sunday and had no idea what happened until she returned on Monday.
"I'm starting to choke. I can't believe it," she said through tears. "My house for 22 years is now....." Cambrara started to say before she was unable to speak any longer.
Cambrara said she had fire insurance but not flood insurance because it was too expensive.
"$3,000? That's too much for me," she said.
Other residents were taken aback by the devastation.
"This is as bad as I've ever seen it and I've been around here for 25 years," said Mike Teal.
"We didn't have enough time to get anything. This is the only outfit I've got," said Pat Rhaes. "It was quick, we had to get out."
Meanwhile, train service at the Trenton Transit Center is shut down after the Assunpink Creek overflowed, flooding the platform. A number of train cars remained underwater on Monday as thousands of commuters figured out what to do next.
"I had to get a ride all the way down here from Jersey City," said Katrina Lovira. "I had to make it all the way here so somebody could pick me up from Pennsylvania."
Fortunately, there has been no loss of life and no major injuries so far.