More than 1,000 Sydney Jews have been left in limbo for Yom Kippur after a fire severely damaged their synagogue on the first night of Rosh Hashanah.

Seven fire trucks were required to extinguish the blaze at Kehillat Masada on Sydney's north shore at around 11pm last Wednesday.

Officers from Fire and Rescue New South Wales rescued the Torah scrolls from the path of the flames and saved the structure of the sanctuary after about three hours of firefighting.

"All the Torah scrolls were rescued, although some are smoke damaged," Masada College president Trevor Lorge said. "None was destroyed."

Mr Lorge, who witnessed the blaze at Kehillat Masada, located within the campus of Masada College, a large Jewish school, said: "It was a very devastating ordeal. It was very, very upsetting."

The blaze was raging, with thick black smoke

Ingrid Shakenovsky, a freelance Jewish photographer, said: "It was raging with thick smoke blanketing the scene. I could see burning orange flames."

The police forensic unit believes the blaze was accidental. The fire also damaged the kitchen, offices, board room and the high-school library.

Kehillat Masada president Cecil Bass said: "We have lost siddurim, chumashim and machzorim as well as tallitot and tefillin. The damage is substantial and it will take many months to repair."

School principal Wendy Barel said that she was devastated by "so much damage and destruction".

"The most important thing is that no one was hurt or injured and that it took place after the premises had been vacated from very busy first night Rosh Hashanah services," she said.

The synagogue has a membership of about 450 families, which swells to more than 1,400 people on Rosh Hashanah and Yom Kippur. Most members dispersed to North Shore Chabad and North Shore Synagogue for the remainder of the festival, Mr Lorge said.

Insurance assessors have already examined the site, which is likely remain closed for up to six months due to renovations.

The board is scrambling to find accommodation for Yom Kippur and is canvassing rental halls as well as a marquee.