Thousands of customers are still without power on Sydney’s northern beaches after the brief but cyclonic weekend storm that felled power lines, leaving a trail of destruction.

Ausgrid has restored power to almost 17,500 customers following Sunday’s storm that ripped through beachside suburbs Narrabeen, Collaroy and Dee Why, leaving more than 500 hazards, like trees on powerlines.

The ferocious storm, which lasted only a few minutes, ripped roofs off apartment buildings and blacked out 35,000 homes.

Susan Cobham, 68, who was heading home from a party near Narrabeen Surf Life Saving Club, died after she and two other women were struck by a massive Norfolk Island pine.

The two injured women remain in Royal North Shore Hospital.

Tweet from @Ausgrid

Ausgrid expects the majority of customers will have power restored in the next few days. However, due to extensive damage at Dee Why, Collaroy, Naraweena and Wheeler Heights, “power outages could extend well into the week”.

Additional crews from neighbouring network Endeavour Energy, and contractors, have been brought in to support Ausgrid’s repair efforts to restore the 17,500 customers who are still blacked out.

“It’s a very difficult time of year to be without power, and we apologise for the delays,” Ausgrid said in a statement.

“We are doing everything we can to turn the lights back on as soon as possible.

“Where we can, we are progressively turning power back on, and as always the safety of our customers and staff remains our number one priority.”

Given the extensive damage from the storm, some parts of the network need to be rebuilt.