Nine Philadelphia police officers fired a total of 109 shots Wednesday night at Christopher Sowell, killing him and ending a rampage in West Philadelphia in which he beat, choked or stabbed five people, including his son and daughter, Commissioner Richard Ross announced Friday.

Ross said he did not know how many times Sowell, 32, was hit, but said most of the wounds were to his lower body.

The commissioner acknowledged that the volume of gunfire was high.

"Clearly, 109 rounds is a significant cause of concern, regardless of what the circumstances are," Ross told reporters gathered at Police Headquarters. "It is not an indictment of the police officers, but it may be a significant training issue we need to address."

He offered an possible explanation for the output: It was the result of "contagious gunfire."

"In a very volatile situation, particularly with a number of officers present, if there is one officer who reacts quicker than the rest and fires — and this was in fact a very dangerous and volatile situation based on what they knew — other officers hear that gunfire, and they believe they are now under fire, and that they return fire," Ross said.

The commissioner did not identify the nine officers. He said their names were expected to be released Saturday, within the 72 hours required under department policy.

The shooting was the 16th officer-involved shooting in the city this year, according to police statistics. Three have ended fatally, including Wednesday's event, and an incident earlier last month when police shot and killed Nicholas Glenn after he went on a shooting spree in West Philadelphia that left one woman dead and five other people — including two police officers — injured.

Sowell was killed outside a home on the 700 block of Cobbs Creek Parkway shortly after 7 p.m. Wednesday, at the end of what Ross has called a "violent rampage" — a rage that police and Sowell's relatives have said was fueled by drugs.

Police said the bloodshed began at Sowell's home, on the 6200 block of Hazel Avenue, when he choked his 12-year-old daughter, stabbed and slashed the throat of his 8-year-old son, and stabbed his son's 13-year-old friend several times in the chest. The girl suffered no major injuries; the boys remained Friday in critical condition at Children's Hospital of Philadelphia.

Shortly afterward, Sowell ran to a family friend's home a few blocks away on Cobbs Creek Parkway. Two women inside, ages 41 and 70, allowed him in to get something to eat, police said. Sowell responded by taking a steak knife and cutting the older woman's throat, and beating the younger woman across her face.

The 70-year-old woman was taken to Penn Presbyterian Medical Center, where she was in critical condition Friday. The younger woman was taken to Mercy Fitzgerald Hospital, where she was listed Friday in stable condition.

Ross said part of the reason responding officers may have opened fire was because they believed they were looking for a gunman. The initial 911 call reported that shots had been fired within the house on Hazel, Ross said, and that same information was broadcast over police radio.

When Sowell came out of the house on Cobbs Creek Parkway, Ross said, officers told him to take his hands out of his pockets several times. When he finally did, he raised his hands "abruptly" with an unknown item in one hand and the officers opened fire, Ross said.

Ross said police did not find a gun on Sowell, but police have said they found a cellphone next to his body. Two houses nearby were each pockmarked by dozens of bullet holes. The glass storm door of one house was also shattered.

Internal Affairs and the Homicide Unit will investigate the shooting, and the officers involved have been placed on desk duty pending the outcome of the investigations.

Ross said the officers involved have yet to be interviewed.