Police are seeking witnesses or anyone who may have information about an assault or possibly a bad fall that left a 17-year-old Santa Rosa boy unconscious with a serious head wound Saturday afternoon on the grounds of Montgomery High School.

The boy, a student at Maria Carrillo High School across town, was found by a passer-by outside Montgomery's gym. He was breathing but unconscious. An ambulance rushed the teen to Santa Rosa Memorial Hospital and he later was flown to Children's Hospital Oakland, where he remained unconscious and in critical condition Saturday night.

He had no identification on him at the time when he was found, which prompted Santa Rosa police to issue a call for public help.

His father read an article about the injured boy online and phoned police Saturday evening. He was able to give a description of the teen and later identify his son at Memorial Hospital.

The boy had suffered a large wound to the back of his head and was found about 3:58 p.m. by a Santa Rosa doctor who had just arrived at the school to walk his two dogs.

The boy was lying on his back and was almost up against the gym's east wall, which faces the school's playing fields, Santa Rosa Police Sgt. John Cregan said.

Darin Brunson, the doctor who found the boy, said that in addition to his head wound, he also saw what appeared to be blood or wounds on the boy's hand or hands near the knuckles.

That observation, the severity of the boy's head wound and his position so close to the gym wall — perhaps ruling out a fall or jump from the gym roof — led officers to suspect he may have been assaulted, Cregan said.

The department's violent crime unit has been assigned to the case.

"But we're not really sure what happened," Cregan said, explaining that an accidental fall or jump from the gym's roof had not been ruled out.

The roof is more than 20 feet above the pavement.

No blood was visible on the wall. Firefighters washed down the pavement after tending to the boy, police said.

Brunson said he saw no other people or suspicious activity in the immediate area when he found the boy. An officer arriving on the scene soon after saw a group of four teens — three girls and a boy — who ran away upon her approach.

In the ensuing pursuit, at least one of the teens was tracked down by officers, but Cregan said the individuals appeared to be runaways from a group home and not connected with the injured boy.

Detectives are looking to interview the boy's friends and others who may have seen him Saturday in the hopes of retracing his steps before he was injured.

They withheld his name because he is a juvenile under the age of 18. It was unclear whether the boy lived near Montgomery.

As police were seeking to identify the teen, Cregan said the boy's parents saw a pressdemocrat.com article about the injured boy.

Cregan said they were traumatized. "They're just dumbfounded as to what occurred," he said.

Anyone with information was urged to call the Santa Rosa Police Department at 543-3600.

You can reach Staff Writer Brett Wilkison at 521-5295 or brett.wilkison@pressdemocrat.com.