Police critically wounded a machete-wielding woman in North Philadelphia yesterday afternoon, less than 18 hours after a shotgun-carrying man was killed by a plainclothes police officer in South Philadelphia, authorities said.

Shortly after 5 p.m., police responding to a call found three young children alone in a rundown house so squalid that child welfare officials were summoned to help remove them, Internal Affairs Chief Inspector William Colarulo said.

When their mother appeared on the scene, she angrily argued with police, and after going into the house, she returned with a machete, made threats, and rushed a female officer with the weapon, Colarulo said.

The officer fired, wounding the woman in the side, and she taken to Temple University Hospital, where she was listed in critical condition this morning, police said.

After midnight, a plainclothes police officer shot and killed a man who barged out of a South Philadelphia house carrying a shotgun and pointed the weapon at uniformed officers, authorities said.

The man, identified by police as Quinzell Elam, 34, had fired the 12-gauge shotgun at least twice inside the house, and a blast hole was evident in the front door yesterday.

Elam was the eighth person fatally wounded in a law-enforcement shooting in the city this year, and the sixth involving the Philadelphia police. Twenty people were killed in police shootings last year.

Chief Inspector William Colarulo, commander of Internal Affairs, said Elam apparently had been involved in a dispute at a nearby bar shortly before the shooting and may have gone home to get the shotgun to settle the score.

He said that shortly after midnight, uniformed officers responded to a call of a person screaming on the 1200 block of South 19th Street in Point Breeze.

When they arrived, they heard two shots inside a rowhouse across the street from the 19th Street Missionary Baptist Church, Colarulo said. As they approached the house, Elam burst out with the shotgun in hand, prompting the officers to radio for assistance and to take cover behind their patrol car.

Two plainclothes officers soon arrived. One of them, after identifying himself as an officer, ordered Elam to drop the weapon, the chief inspector said.

Elam was attempting to chamber a round and pointing the shotgun at the uniformed officers when the plainclothes officer fired once, hitting the gunman in the left side, Colarulo said.

Elam died at 2:53 p.m. at the Hospital of the University of Pennsylvania, police said.

Colarulo said police recovered two spent shells and a number of unspent shells from Elam and on the street.

The officer has been placed on administrative duty while Internal Affairs and the District Attorney's Office investigate the shooting, as is standard procedure.

Authorities said that no one else was injured and that the screaming that brought police to the block in the first place may have come from Elam himself.

Court records show that Elam had convictions for theft in the early 1990s but that he had had no run-ins with the law since 1994.

Theresa Gregory, who said she was the aunt of Elam's girlfriend, said he was known as "Q" and was the father of two children ages 5 and 9.

In the neighborhood, many had heard the shooting but few knew what happened. On 19th Street, an elderly member of the church who asked not to be identified pointed to an abandoned house next to the church and said it is used by drug dealers and drug users.

He said efforts to get the building torn down had been unsuccessful.