A gunman opened fire on a woman believed to be his sister inside a West Philadelphia home Friday as officers were speaking with her, police said. The shooting then devolved into a hostage situation with six people, including children, were held against their will until SWAT officers moved in.

The incident began around 4:20 p.m. when officers were called to the home along the 200 block of S. Millick Street because of an argument between a man and woman, police said.

Philadelphia Police Commissioner Richard Ross said officers were invited into the home and were speaking with a woman who said her 24-year-old brother was assaulting their mother. Moments later, police said he appeared in the kitchen and began shooting.

"They initially had a conversation with the female and then he appears in the rear of the home and he starts discharging and that’s when it all jumps off," Ross said.

An officer returned fire as he and his partner took cover behind a parked car. Ross said the 28-year-old woman then escaped the home, nursing a gunshot wound to the arm, and moved next door. Officers were able to get her away from the home.

She was taken to a nearby hospital for treatment.

The gunman, identified by police as Kadeem Nelson, remained inside the home, along with two adults and four children, as police called in the SWAT unit to negotiate with him.

Nelson was hit several times by police gunfire, officials said.

Ross said the two adults helped provide police with information as the barricade carried on.

SWAT officers moved into the home around 5:40 p.m. and a short time later secured the scene. The children and two adults were spotted milling on the home's porch as the alleged shooter was taken out of the home on a stretcher. His wounds aren't believed to be life-threatening, Ross said.

No one else was hurt, police said. A .380 caliber semi-automatic handgun was recovered in the home.

The incident remains under investigation.