At least 11 people died when a man entered a synagogue in the US city of Pittsburgh and opened fire on Saturday.

The shooter entered the Tree of Life Congregation Synagogue in the city's Squirrel Hill neighbourhood at around 10am local time, during a baby-naming service.

Six people were injured, including four police officers.

The Anti-Defamation League said it was the deadliest attack on the Jewish community in US history.