ERIE, Colo. (AP) — Four of the five people killed in a small-plane crash north of Denver were identified Monday as a woman and her three children.

The Weld County coroner says Tori Rains-Wedan, 41, and her three sons, 15-year-old Mason Wedan and 11-year-old twins Austin and Hunter, died in the crash Sunday, the Boulder Daily Camera reported.

Officials haven't named the pilot of the Piper PA-46 who also died when the plane crashed about 11:50 a.m. in a grassy field near the Erie Municipal Airport, about 20 miles north of Denver.

Rains-Wedan owned Educated Minds, a company that offers education classes to real estate agents, the newspaper reported.

Grief counselors would be provided to students and staff Tuesday at the schools the boys have attended, Boulder Valley School District spokesman Briggs Gamblin said.

The six-passenger plane crashed a few hundred yards northwest of the runway, Erie Police Cmdr. Lee Mathis said. Three people were declared dead at the scene, and two were taken to hospitals.

Jan Culver told the Daily Camera that she was with a friend in a pasture near the airport when she heard the plane and saw it flying "really, really low."

"We heard it sputtering," she said. "Then there was no sound. We knew it was a crash."

Culver said the crash produced a small cloud of dust and she went to help because she has some medical knowledge.

"It was a plane upside down with some folks already out of the plane," she said. "I could tell there were some bad injuries."

The Denver Post reported that NTSB records show the airport was the scene of three crashes in 2013 and two in 2012. None of those incidents had a fatality.

The National Transportation Safety Board was investigating Sunday's crash.