Roads have been blocked by mudslides, communities cut off and 1,800 trucks stranded as the tunnel through the Andes to Argentina has been closed.
Rain has been falling for more than a week, causing devastation across much of the region.
At least 10 people died in a mudslide in the southern town of Chiguayante, three of them firefighters.
Many others are missing, including several fishermen.
More rain expected
Rivers have burst their banks, causing extensive damage to tens of thousands of homes, while whole communities have been evacuated.
Fallen trees and telephone poles, as well as the mudslides, have blocked roads.
Police, army and firefighters are working with local authorities to bring food, medical supplies and blankets to the worst affected communities.
Chilean President Michelle Bachelet declared a state of emergency after visiting the region and said Chile was responding well to the crisis.
But not everyone was pleased to see her, some accusing her of opportunism to boost her falling popularity in the opinion polls just months after she took office.
She responded by saying she simply went where the problems were to find solutions to the people's suffering.
"I need to see with my own eyes what the people need," added Dr Bachelet.
Weather forecasters in Chile expect more rain over the weekend, although less severe than in recent days.Last Mod: 20 Eylül 2018, 18:16