The arm of a landscape worker was cut off Monday morning after he was run over by a lawnmower he was riding, MyFoxColorado.com reported Tuesday.

The worker was mowing a steep hill when he reportedly lost his balance and fell off the mower. The machine then turned on him and ran over him, severing an arm.

The accident happened across the street from the Denver Broncos Alumni Golf Tournament in Broomfield, Colo.

“We were about to tee off and the helicopter landed on the tee box,” golfer Daniel Adler told FOX 31 News. “They put his arm in an ice box.”

Commercial lawnmowers traditionally have a safety mechanism installed in them that mechanically shuts off the mower if someone falls off, rescue crews said.

"Obviously the machine did not shut off as it should have," Wendy Forbes of North Metro Fire Rescue told the news station.

Click here to watch the video report on myfoxcolorado.com.