A three-alarm fire in Lynn displaced 31 people on Tuesday night, fire officials said.

Firefighters responded to the scene of the blaze at 152-156 Chestnut St. at about 11 p.m. Firefighters had difficulty getting to the back of the building because the gate in the alleyway was locked, officials said.

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The Red Cross was called in to help house the displaced residents, which included seven children. No injuries were reported.

Swampscott and Saugus Fire Departments assistend in knocking out the fire, officials said. 

The cause of the fire and the cost of damage is still unknown.