Residents evacuated after explosion tears through Sydney apartment

Dozens of people have been evacuated from an apartment block in Sydney after a unit exploded and caught on fire.

Residents on Mackinder Street in Campsie were forced to flee after a "huge" explosion tore through the block just before 8pm.

Isaac Viglione was at a friend's apartment two doors down from the blast.

"We heard a huge explosion," Mr Viglione told 9NEWS.

"We ran to the balcony and looked across to see fire bursting out.

"We immediately ran down the fire stairs."

Mr Viglione said at least 100 people were evacuated due to the fire.

Fire and Rescue NSW have extinguished the fire, but it is not known if anyone was injured in the blast.

This is a breaking news article. More information will be added as it comes to hand.

Do you know more? Email contact@9news.com.au