The bodies of four people, including two "young children" were found in an Arlington, Mass., apartment on Monday.
WCVB reports the deaths were being investigated as homicides.
"I'm heartsick for the kids. It's heartbreaking," neighbor Amy Iannelli, 74, told the Boston Herald.
Arlington Patch reports that authorities are trying to notify next of kin before providing the public with more details.
UPDATE: News reports indicate the four dead are husband, wife and two boys under the age of 1.
This is a developing story.
CORRECTION: An earlier version of this story incorrectly said the four dead were victims of a house fire.