Authorities in the US state of Colorado said nearly 1,000 homes and other structures were destroyed, hundreds were damaged, and three people were reported missing in a wildfire that incinerated numerous neighborhoods in a suburban area at the foot of the Rocky Mountains, reports the Associated Press.

Boulder County Sheriff Joe Pelle said on Saturday that investigators are still trying to identify the cause of the fire.

Pelle noted that utility officials did not find any broken power lines in the area where the fire broke out. He said the authorities are reviewing a number of reports and have issued a search warrant for one specific location. He declined to provide details.

In turn, an anonymous source confirmed that one site is being inspected in Boulder County in the Marshall Mesa open grassland area, about 2 miles (3.2 km) west of the fire-affected city of Superior.

Access to the site, which was only one of several under investigation, was blocked by the National Guard, the source said.

Officials previously believed that at least 500 homes, possibly 1,000, had been destroyed by fire, which posed no threat by Friday.

The authorities had previously stated that there were no missing persons. It was later stated that this was due to confusion over the emergency.

Pelle said authorities are organizing brigades to search for bodies and missing persons in the Superior area and in Boulder County, outside the county. According to him, the task is complicated by the wreckage of destroyed buildings.

At least 991 homes and other buildings were destroyed, Pelle said: 553 in Louisville, 332 in Superior and 106 in unincorporated parts of the county. Pelle warned that this count is not final.

At least seven people were injured in wildfires in Louisville and Superior, neighboring towns 20 miles (32 km) northwest of Denver with a total population of 34,000. The fire burned out at least 9.4 square miles (24 square kilometers).