Evan McManus was last heard from on April 2nd, 2014 (Credit: Ashley Ritten)

By JONAH LUSTIG and SABRINA ELFARRA

Rescue teams are calling in reinforcements as they hold out hope they can brave tough conditions to find two missing hikers presumed lost in the Colorado Mountains.

The National Guard has joined a team of 20 volunteers in the search for Damian McManus, 51, and his son Evan, 18, who have been missing since last Wednesday, according to Bill Barnwick of the Alpine Rescue Team. The father and son from St. Louis Park, Minn., never returned from a day hike in a popular Colorado park area where they were for the 18-year-old's spring break.

"We have no idea what peak they were on or where they were going," Barnwick told ABC News. "We have no direction of travel or any idea what kind of equipment they are using."

McManus and his son were set to return to Minnesota over the weekend and never returned to their car or hotel after hiking at Echo Lake in Clear County, about two hours from Denver.

Barnick said that volunteers are currently braving 20 mile-per-hour winds and five feet of snow, and that it has been snowing on and off since the search began. He summed up the conditions in one word: "Terrible."

Despite these conditions, rescue teams remain hopeful. Family and friends have set up a Facebook group to encourage support for the rescue mission, which has attracted over 2,000 members since its creation Sunday. A family friend who wishes to remain anonymous says that a fund has been set up to provide support to the family. She says those who wish to contribute can use the following bank information to donate:

Citizens Independent Bank 5000 West 36th Street SLP MN 55416 Attn: Lambert Lum 952-926-6561