“It was an ambush,” Allegheny County District Attorney Stephen A. Zappala Jr. told reporters Thursday.

AD

Zappala offered a grim accounting of the attack, describing one attacker firing at people behind the house to drive them toward the home — and right into the path of another attacker firing a rifle at their heads.

AD

“It was premeditated, it was calculated, it was planned,” Zappala said during a briefing. “It’s just a brutal murder. It’s one of the most brutal I’ve seen. I’ve been the D.A. for 18 years, I haven’t seen something like this during my tenure.”

Investigators were looking at possible suspects, but they “don’t have enough” to arrest or bring anyone in yet, Charles Moffatt, superintendent of the Allegheny County Police Department, said at a news conference Thursday afternoon. But he said police had not determined a possible motivation for the attack.

AD

“It could be anything,” said Moffatt, who has announced plans to retire later this month. “Everything is on the table.”

The Allegheny County police said that a 911 call came in shortly before 11 p.m. Wednesday about a shooting at a home in Wilkinsburg, a small borough just east of Pittsburgh. Police said they found four people dead on the home’s back porch — three women and a man — and another four who were injured. All eight had been shot during what appeared to be a cookout in the back yard, authorities said.

The man was shot and went down trying to get into the doorway, and the three women were shot trying to get over him and into the house, Moffatt said.

AD

AD

A woman who was injured in the shooting died at a hospital. Two men who were injured remained in critical condition Thursday, while another woman was treated and released.

Children inside the home at the time of the shooting were not injured, according to Moffatt.

Allegheny County officials on Thursday morning identified the five people killed as Tina Shelton, 37; Shada Mahone, 26; and three siblings: Jerry Shelton, 35; Brittany Powell, 27; and Chanetta Powell, 25. Authorities did not immediately identify a cause of death for them, though police had said all of them were struck by gunfire.

Zappala said the pregnant woman — identified later by police as Chanetta Powell — was due to give birth in May.

AD

Moffatt told reporters that the medical examiner’s office had officially deemed the unborn baby a homicide victim, which he said pushed the death toll to six.

AD

“It just breaks my heart,” Jessica Shelton, who said she lost three of her six children and two nieces in the attack and that one of the men in the hospital is her son, said during a tearful news conference Thursday.

Shelton mentioned that in addition to her relatives, there were other people — “three young gentleman” — who attended the cookout, and questioned how they avoided injury.

“My whole family was massacred,” she said. “Why didn’t these three guys get hurt?”

Zappala said that authorities believe “possibly one, maybe two people were targeted,” while the other victims appeared to be innocent bystanders. He said that investigators were working through a number of potential theories behind the shooting and had “eliminated a couple of different possible motives.”

AD

Police have not recovered the weapons so far, but they found 48 shell casings at the scene, Moffatt said.

The Bureau of Alcohol, Tobacco, Firearms and Explosives joined the investigation Thursday and was offering a $20,000 reward for help, according to Christopher Taylor, assistant special agent in charge of the bureau’s Philadelphia division.

Authorities recounting the chaotic scene that unfolded Wednesday night said people fleeing the initial gunfire were driven into a hail of bullets from a second shooter.

AD

“It looks like right now they were all fleeing toward the back door of the residence when the second gunman fired from the side of the yard,” Lt. Andrew Schurman of the Allegheny County police told reporters at a different briefing after the shooting. “And they all seemed to get caught on the back porch.”

AD

Zappala said that the first attacker used a .40-caliber handgun to fire at people behind the house, while another attacker wielding what he called “an AK-47-type” rifle was waiting for them when they headed toward the home.

“They just pushed them toward the door, and right into the path of the rifle,” Zappala said.

Photos from the scene showed a residential street littered with police evidence markers.

“This street is always quiet. There is nothing but kids on this street,” Kayla Alexander, a local resident, told WPXI. “I’m shaken, so it’s pretty bad.”

AD

This rampage is the latest in a series of shooting sprees that have shaken communities nationwide, coming just weeks after attacks in Hesston, Kan., and Kalamazoo, Mich. Since last year, mass shootings have erupted at locations as disparate as a holiday party in San Bernardino, Calif.; a community college in Roseburg, Ore.; and a church in Charleston, S.C.

“Wilkinsburg is a community filled with grief, shock and anger this morning,” Allegheny County Executive Rich Fitzgerald said in a statement Thursday. “We share their grief and offer them our support in the days and weeks to come.”

AD

The community in Wilkinsburg, not far from affluent neighborhoods in Pittsburgh, has faced problems with its schools and grappled with poverty. Wilkinsburg has about 15,000 residents, and it is poorer than surrounding Allegheny County as well as the state; one in five Wilkinsburg residents are living in poverty, according to census figures.

AD

“We are devastated and saddened by this news, and we will not be complacent and let our homes, our streets and our neighborhoods be taken from us,” Patrick Shattuck, president of the Wilkinsburg Borough Council, said in a statement.

Shattuck said that Wilkinsburg residents awoke Thursday ” as a top story on the national news and in headlines,” and vowed that the community would continue to rally together in the face of the attack after the national attention faded away.

Michael Miller contributed to this post, which has been updated.