Unprecedented -- that's what the National Weather Service is saying about the flooding in and around Houston from what is now Tropical Storm Harvey.

More than 1,000 people had to rescued there overnight Sunday. Roads have turned to rivers and parking lots to ponds. Boats have became the best way to get around and rescue those trapped in their homes.

Emergency response crews from across the nation, including Arizona are now in Texas, helping with this catastrophic natural disaster.

Eighty members of the state's Urban Search and Rescue Team packed up Saturday night. They left in a caravan of vans and boats and are expected to arrive in Texas Sunday night and get right to work.

Up to 50 inches of rain could fall in some areas in Texas and cause what's being called a 500 year flood.

Air rescues are happening non-stop. And the Arizona National Guard has sent four helicopters to Texas to help.

Meanwhile, 19 American Red Cross volunteers from Arizona, including Connie and David Icenhower, are in Texas helping the Harvey's victims. The two veteran volunteers packed up an ERV, Emergency Response Vehicle and headed out Saturday morning. They'll be handing out water, food, clothing and other supplies to those who've lost everything.

“This is such a large, vast area and there's still so much rain still coming, heaven knows where the need is going to be tomorrow,” said David Icenhower.

The Red Cross expects the disaster relief for the storm to cost at least $10 to $20 million. If you'd like to donate to help the victims, the Red Cross has information here.