(CNN) -- Three Michigan children reportedly left alone in their family's apartment died in a fire Monday afternoon, a public safety official said.
The fire broke out around 2 p.m. in Kalamazoo, said Brian Uridge, assistant chief of public safety. Two of the children were 3 years old, and the third was 1, Uridge said.
"You could see smoke from blocks away," Uridge said. The main floor of the apartment building was engulfed in flames when firefighters arrived, and "they found three kids who had already perished as a result of the fire," he said. The cause of the fire is unknown, he said.
The children's parents were at the scene, Uridge said.
"Initially, we have information that the kids were left alone in the apartment, but we can't talk about charges because it's too early in the investigation," Uridge said.
The victims' identities have not been released.