Three young children, including a baby, were alone in a St. Louis apartment Sunday when a fire broke out in the building, killing the infant and critically injuring the others, authorities said.

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According to KSDK-TV, firefighters said the blaze began about 1:30 p.m. on the top floor of a three-story building on Kealty Lane. After calling 911, neighbors reportedly tried to save the children, kicking down the locked door before the billowing smoke forced them to retreat.

When emergency crews arrived, they discovered the baby dead inside the apartment, KTVI reported. The two surviving children were rushed to a nearby hospital, where they remain in critical condition, officials said.

Although authorities have not revealed the victims' names or ages, a family friend told KTVI that the older children are 5 and 3.

It wasn't immediately clear what caused the fire or whether anyone could face criminal charges in the incident.

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