Survivors are recounting the terror of hiding in a cupboard during the massacre that left 11 people dead at a Pittsburgh synagogue – and asking why the gunman blamed them for the world’s problems.

Suspect Robert Gregory Bowers is expected to appear in federal court after the mass shooting on Saturday morning.

Authorities say he expressed hatred toward Jews during the rampage and in later comments to police.

US attorney Scott Brady said federal prosecutors intend to pursue the death penalty.

Synagogue shooting vigil
The Anti-Defamation League called it the deadly attack on Jews in US history (AP)

Barry Werber said members of the Tree of Life Synagogue’s New Light Congregation were in the basement and beginning to pray when they heard crashing coming from upstairs. They looked out, and saw a body on the staircase.

Mr Werber said he called 911 but was afraid to say anything for fear of making noise as gunshots echoed out.

Rabbi Jonathan Perlman closed the door and pushed them into a large supply cupboard, he said.

When the shots subsided, he said, 88-year-old Melvin Wax opened the door, only to be shot and fall back inside.

“There were three shots, and he (Mr Wax) falls back into the room where we were,” he said. “The gunman walks in.”

A memorial to the victims
A memorial to the victims (AP)

Apparently unable to see Mr Werber and the other congregants in the darkness, Bowers then walked back out.

The 76-year-old Mr Werber said of the gunman: “I don’t know why he thinks the Jews are responsible for all the ills in the world, but he’s not the first and he won’t be the last.

“Unfortunately, that’s our burden to bear. It breaks my heart.”

Bowers opened fire with an AR-15 rifle and other weapons, killing eight men and three women before a tactical police team tracked him down and shot him, according to official documents.

He apparently posted an anti-Semitic message on a social media account linked to him just a few minutes before he allegedly opened fire.

Bowers expressed hatred of Jews during the rampage and later told police that “I just want to kill Jews” and that “all these Jews need to die”, authorities said.

Jeffrey Myers
Rabbi Jeffrey Myers, right (AP)

The Anti-Defamation League called it the deadliest ever US attack on Jews.

Six people were injured, including four officers.

Bowers underwent surgery and remains in hospital.

The dead were 97-year-old Rose Mallinger; brothers Cecil and David Rosenthal, 59 and 54 respectively; husband and wife Sylvan and Bernice Simon, 86 and 84 respectively; Melvin Wax, 88; Dr Jerry Rabinowitz, 66; Joyce Fienberg, 75; Daniel Stein, 71; Richard Gottfried, 65; and Irving Younger, 69.

All three congregations at the synagogue were conducting Sabbath services when the attack began just before 10am on Saturday in the tree-lined residential area of Squirrel Hill, about 10 minutes from the centre of Pittsburgh and the hub of the city’s Jewish community.

Speaking at a vigil in Pittsburgh on Sunday night, Tree of Life Rabbi Jeffrey Myers said about a dozen people had gathered in the main sanctuary when Bowers walked in and began shooting. Seven of his congregants were killed, he said.

A shooting memorial
A memorial for those killed and injured takes place at Temple Israel in Crystal, Minneapolis (Richard Tsong-Taatarii/AP)

“My holy place has been defiled,” he added.

Mr Werber called the gunman “a maniac” and “a person who has no control of his baser instincts”.

Bowers was a long-haul trucker who worked for himself. Little else is known about the suspect, who had no apparent criminal record, and it appears he acted alone.

The suspect was charged with 11 state counts of criminal homicide, six counts of aggravated assault and 13 counts of ethnic intimidation. He was also charged in a 29-count federal criminal complaint that included counts of obstructing the free exercise of religious beliefs resulting in death – a federal hate crime – and using a firearm to commit murder.

Of the six survivors, four remained in hospital on Sunday night, and two – including a 40-year-old police officer – are in a critical condition.