CONIFER, Colo. (AP) -- Authorities said Friday they are investigating how well an emergency telephone notification system worked during a deadly Colorado wildfire because some residents who signed up never got a warning.
About 12 percent of the people authorities intended to notify didn't get a warning Monday about the wildfire in the mountains southwest of Denver. Jefferson County sheriff's spokesman Mark Techmeyer said some of those people likely hung up after hearing a pause that precedes the automated message, or their phone lines may have been busy.
He said that is bound to happen in any emergency, but authorities were most concerned that there wasn't any attempt to reach an unknown number of additional people registered to get the telephone alerts.
"We want to get to the bottom of this as much as our citizens do," Techmeyer said.
The company that handles the system, Baton Rouge, La.-based FirstCall Network Inc., said it worked exactly as it should have. FirstCall provides the alert service to as many as 200 agencies nationwide.
"I know that everyone who opted in got the call," FirstCall President Mark Teague said Friday. "We're working closely with (county officials) trying to get them all the information they need."
FirstCall's system is set up to call three times at three-minute intervals if a phone line is busy, Teague said. Local agencies can change that if they wish and can also decide what message appears on a recipient's telephone if it has caller ID. Jefferson County's system also sends text messages, FirstCall said.
Monday's calls went out in two waves. The first included people outside the evacuation area and even outside Colorado, Techmeyer said. He didn't know the times of the two waves.
Sheriff's officials said a couple found dead in the fire zone got a call, as did a woman who remains missing, but it wasn't immediately clear when the calls came.
About 500 firefighters have contained 45 percent of the 6-square-mile wildfire, which was apparently sparked by a state controlled burn that sprang to life in strong winds. The fire damaged or destroyed at least 25 homes, and residents of about 180 homes remain evacuated.
Rescuers were still searching for Ann Appel, reported missing since Monday, while a memorial service was held for Sam Lamar Lucas, 77, and Linda M. Lucas, 76.
On Friday, the Colorado State Forest Service released its plan for the controlled burn, showing that planners acknowledged there was a potential for fires to escape and cause a "significant threat" to nearby homes.
However, officials thought it was more likely they'd be able to put out any fire before it got that far, partly because of crews and water on site. Officials who wrote the plan insisted that the forest thinning would help protect those homes from a potential wildfire in the future.
The plan dates from 2006 and covers a series of burns being done in the area for Denver Water.
Under the plan, nearby residents were supposed to get warning letters. The state Forest Service has refused to say if that happened, citing an independent review into the burn.
Gov. John Hickenlooper suspended prescribed burns on state land after the Forest Service said the controlled burn apparently triggered the wildfire. On Friday, the U.S. Forest Service said it was suspending prescribed six planned burns in Colorado until the weather improves. Several more Colorado counties enacted fire restrictions Friday.
The month of March is the driest on record in the Denver area, National Weather Service meteorologist Lisa Kriederman said. More gusty winds and warm weather raised the fire danger for much of the state through the weekend, but a cold front promised to bring some snow, and relief, late Sunday, Kriederman said.
Power was restored to some areas and an overnight shelter closed as residents tried to return to normal.
Bill Suvada Jr. said he returned home Thursday but was keeping his car packed in case he has to flee again.
"It was a long night of wondering," Suvada said of his first night home.
Associated Press writers Colleen Slevin and Dan Elliott in Denver contributed to this report.