A Sonoma man who was crushed by part of a large tree that was being cut down and hoisted into the front yard of a house east of town remained in critical condition Friday at John Muir Hospital in Walnut Creek, a hospital representative said.

Jarrad Plaskett, an arborist involved in the tree removal, suffered extremely serious injuries in the 11:40 a.m. accident on Lovall Valley Court, authorities said.

Best friend and roommate Nick Kardum said Plaskett, 33, was in stable condition and sedated.

A Sonoma Valley Fire paramedic said the chunk of tree that fell on him probably weighed hundreds of pounds.

"I think well over 1,000 pounds," paramedic Gabe Stirnus said. "Maybe several."

Plaskett was in group of about three people from Ironbark Arborists hired to cut down several large evergreen trees growing behind the rural Sonoma home, a Cal-OSHA spokesman said.

A Precision Crane Service operator was on the scene to move the cut trees from the back to the front of the house so they could be cut into smaller pieces. A wood chipper was being used to dispose of some parts of the tree, Cal-OSHA spokesman Peter Melton said.

The third tree had been cut down, had been moved to the front and was being lowered to the ground when it unexpectedly broke in half — one half of it falling upon Plaskett, Melton said.

It remained unknown how or why Plaskett was under the tree, apparently against standard safety procedures, he said..

"The workers couldn't understand why he would go underneath the moving tree," police Sgt. Spencer Crum said.

"You just don't know what was going through somebody's mind at the time," Precision Crane Service owner Bud Elliff said. "I guess I don't know. ...Nobody would ever get under a load under any circumstances."

Elliff said the crane operator, an out-of-county resident, was "really shook up" by the incident, though it remained unclear what caused it.

"Nobody wants to see anybody get hurt on a job site," Elliff said. "It was a freak, freak deal."

Plaskett grew up in Sonoma and has family around the area who were at the hospital with him, Kardum said.

The tree removal had been halted, meanwhile, and the crane moved from the site, Melton and Elliff said.

A Cal-OSHA team was at the site Thursday interviewing witnesses and was to return Friday for additional investigation, Melton said.

Calls to Ironbark Arborists on Friday morning were not returned.