Three children are among the dead following an explosion in an apartment building outside Paris, bringing the death toll to eight on Monday.

Eleven people were injured in the explosion that occurred Sunday in a four-story apartment building in the Paris suburb of Rosny-sous-Bois, including four with serious injuries.

The dead include a 40-year-old mother and her 14 and 18 year-old children, a 10-year-old child, a woman in her 80s who lived on the first floor, a 45-year-old woman, a man described as a man in his fifties and another adult.

Rescue workers continued to search for survivors Monday using dogs and machinery.

Firefighters and local officials believe a gas leak from a faulty boiler was the source of the explosion.

“This boiler was located in a ground floor flat,” said Samuel Bernes, a spokesman for the Paris firefighters department. He said the boiler was taken by police for testing.

7 confirmed dead from building explosion in Paris suburb: http://t.co/xiaFyantC5 pic.twitter.com/y5OWt9VEaV

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Neighbors said the blast, which happened at around 7 a.m. local time Sunday, was very powerful.

“Our house moved, we were trembling from fear,” said a neighbor. The sound of the explosion was so loud “our ears were ringing.”

Death toll in Paris building blast rises to 6 http://t.co/6EgxEqQcSX pic.twitter.com/TvTnOJi1y9

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Ghislaine Poletto, 55, who lives about 50 yards away from the collapsed building, said she rushed to the site and helped neighbors “pull two children out.”

One rescued child was “protected by a mattress and a board above his head, which saved his life,” she said.

Two people have been killed after an explosion levelled an apartment block in Paris. #9Newscomau #9News pic.twitter.com/U4J2Ziub5C

— Nine News Australia (@9NewsAUS) August 31, 2014