Two hospitalised after BBQ gas bottle explosion on Sydney's Northern Beaches

Two people have been hospitalised and dozens evacuated after a barbeque gas bottle caught fire and exploded at an apartment complex on Sydney's Northern Beaches.

Emergency services were called to Pittwater Rd in Collaroy after a fire broke out on a balcony about 8.30pm yesterday.

The blaze started on the ground floor building before it began spreading into the upper levels, requiring 50 residents to evacuate.

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Firefighters managed to extinguish the fire within around half an hour.

A male, aged in his 20s, was taken to Royal North Shore Hospital with minor burns and another patient was transported to Northern Beaches Hospital for smoke inhalation.

Fire and Rescue Superintendant Adam Dewberry said the incident served as a reminder that barbeques can be dangerous.

"Due to the number of barbeque fires, particularly on balconies, we're just asking people to be really careful with them, make sure you turn off the gas once you're finished with it," he said.

"Make sure the gas isn't leaking and check the connection, and make sure you've got a bit of separation or distance between the barbeque or any hotplates around."