(CNN) -- The Colorado Forest Service apologized Wednesday for a wildfire attributed to a "controlled" burn that got out of control, killing at least two people, and the governor announced a suspension of such burns.
"This is heartbreaking and we're sorry," State Forester Joe Duda told reporters about the Lower North Fork Fire, which has scorched thousands of acres in Jefferson County, destroying or damaging 27 houses and leaving a woman missing in addition to the two fatalities.
A team is being formed to investigate how last Thursday's controlled burn re-erupted on Monday as a wildfire. "We had made previous patrols in that area and seen absolutely no sign of smoke," he said. "When the winds kicked up strong in the afternoon was when the event started." He expected the investigation to begin within a week, and to be completed within three weeks.
Gov. John Hickenlooper joined the call for an independent review. "The loss of life and property this week is devastating and this fire is far from being contained," he said in a news release. "That's why our top priority remains working to control the blaze."
He suspended the use of prescribed burns by state agencies on state lands -- including state parks, refuges, State Land Board lands and any agency that manages lands -- or under contract on non-state lands, such as by the Colorado State Forest Service. The suspension will be effective until the review of protocols and procedures of prescribed burning is complete.
"We encourage any other land manager who uses prescribed fires as a tool to mitigate fire danger to review their procedures and protocols and carefully evaluate weather and landscape conditions," he said.
Hickenlooper authorized Wednesday the use of two more UH-60 Blackhawk helicopters flown by the Colorado Army National Guard to help subdue the fire. Each helicopter carries a 500-gallon bucket to drop water on the fire. Two other helicopters began flying Tuesday over the fire.
The efforts of more than 500 firefighters made progress Wednesday against the fire, a spokeswoman for the sheriff's office said.
"We have had a good day, a very successful day on this fire," with about 15% containment after 4,140 acres had been scorched, Public Information Officer Jacki Kelley told reporters.
The search continued Wednesday for a woman who was last seen after the fast-moving wildfire swept through her home in a mountainous area near Denver. A search-and-rescue team of 32 people and six dogs searched 60 acres Wednesday around her house and found no sign of the woman, she said. "The scene is still hot, difficult to work in, hard to move dogs in," she said.
Firefighters have dropped 4,100 gallons of fire retardant on the blaze, which was fueled by high winds and dry conditions, she said.
Jefferson County Coroner John Graham identified the dead as a married couple, Samuel Lucas, 77, and Linda Lucas, 76. "They were found very close together," Kelley said. "One was found outside; one was found inside."
Officials were trying to determine why the couple did not leave the fire zone by Monday night.
CNN's Tina Burnside, Phil Gast, Darrell Calhoun, Josh Levs, Shawn Nottingham, Dave Hennen, and Sarah Dillingham contributed to this report.