From left to right, Laura Tyson, Tod Smith and Rebecca Caldwell, residents of Eldorado Springs, watch as the NCAR Fire burns Saturday in Boulder, Colorado.
CNN  — 

All evacuation orders have been lifted after 19,000 residents were told to flee as the NCAR Fire ripped through part of Colorado, officials said.

Residents were allowed to return home Sunday evening, the Boulder Office of Emergency Management said in a news release.

“With the exception of NCAR Road, all roads in the area are now open. Officials anticipate that NCAR Road will remain closed for several days,” the agency said Sunday evening.

“While it is now safe to return home, people in the area of the fire should remain vigilant. Fire officials do not anticipate fully extinguishing the fire for several days. It is possible that the (city may) issue new evacuation orders if conditions deteriorate. Continue to follow this Boulder Office of Emergency Management page for updates.”

The cause of the wildfire remains under investigation.

The inferno broke out Saturday afternoon and burned out of control Saturday evening – prompting evacuation orders for thousands of residents, officials said.

“Evacuation areas include 19,000 people and 8,000 homes,” the Boulder Office of Emergency Management tweeted Saturday evening.

By Monday afternoon, the blaze had charred 190 acres, and that number was holding. The fire was about 68% contained, the office of emergency management said.

A helicopter flies above smoke from the NCAR fire Saturday.

No injuries had been reported, and no structures had been damaged, the agency said late Sunday.

Officials said a combination of cooler temperatures and stellar firefighting efforts helped keep the wildfire from scorching properties and injuring residents.

Mike Smith of the Boulder Incident Management Team said he was “very happy” with the battle against the blaze.

“We had over 200 firefighters from over 30 agencies,” Smith told reporters Sunday. “That, combined with all of the fuel mitigation treatments that we’ve done in this area, is one of the reasons that we had such great success.”