Volunteers from Arizona are lending a helping hand to Colorado flood victims.
The American Red Cross Grand Canyon Chapter said 13 Arizona residents are already in Colorado, en route or making plans to travel.
The volunteers are nurses, case workers, truck drivers, disaster assessment experts and disaster mental health workers.
Thousands of residents have poured out of the mountain towns around Boulder over the past week, fleeing unprecedented floods that tore down hillsides, carried away homes and piled slabs of highway like stacks of books.
Across the foothills, rescuers made progress against the floodwaters. But they were still unable to go up many narrow canyon roads that were either underwater or washed out.
Meanwhile, President Barack Obama signed a disaster declaration and ordered federal aid for Colorado. The White House said in a statement Saturday night that the action makes federal funding available to affected individuals in Boulder County. The government said that other counties could be added later.
On Saturday, the surge of water reached the plains east of the mountains, cutting off more communities and diverting some rescue operations.
Four people have been confirmed dead since the harrowing floods began Wednesday. And hundreds of others have not been heard from in the flood zone, which has grown to cover portions of an area nearly the size of Connecticut.
Some of those who are unaccounted for may be stranded or injured. Others might have gotten out but not yet contacted friends and relatives, officials said.
Copyright 2013 CBS 5 (KPHO Broadcasting Corporation). All rights reserved. The Associated Press contributed to this report.