Springville police served a search warrant Sunday night as they tried to determine what killed a 35-year-old man earlier in the afternoon.

Just after 3:30 p.m., the man was found lying on the floor of his home near 2500 S. El Dorado by officers who responded to a report of a carbon monoxide problem, said Springville Police Lt. Dell Gordon.

A woman who was visiting the home called 911 after her daughter and grandchildren complained of illness. The woman suspected it was caused by carbon monoxide, police said.

"Her daughter told her that all the kids have been sick and her husband is down on the floor," Gordon said.

The woman told dispatchers that the man could not be moved but evacuated everyone else from the home. Medical responders tried to resuscitate the man at the scene. He was taken to a nearby hospital where he was pronounced dead, Gordon said.

Firefighters checked the home for carbon monoxide but did not find any, officials said. Questar Gas employees shut down gas to the home and checked appliances but could not find any problems.

"The fire department opened windows and ventilated just in case," Gordon said. "If there was carbon monoxide, even though they ventilated, there are still going to be pockets in the closet and so forth."

A woman and her two children were also taken to the hospital, where they were reported in good condition, police said.

Before she was taken to the hospital, officers asked the woman for permission to search her home, Gordon said.

"She denied them," he said.

Investigators executed a search warrant Sunday night. Officers were in the home around 8 p.m., Gordon said. Police did not immediately release the findings of the search Sunday night.

"At this point, it's an unattended death," Gordon said. "We don't know what caused it. That's what we have to determine."

Police did not release the man's name Sunday.