Crews started searching the waters of the Farmington River on Thursday, July 15 for the two boys, both of Plainview, where they were last seen swimming.
The search was called off at nightfall, but returned early Friday, July 16, officials said.
Plainville police, state police, and the Deep officials are involved in the search.
Connecticut State Police said on Friday a Silver Alert has been issued for the two, including 17-year-old Anthony Nagore and 15-year-old Lucas Brewer.
Personal belongings, including their cellphones and clothing, were found on the banks of the river.
To help find the teens, state police have sent a dive team and the New Milford Police Department is providing helicopter support.
Police are set to provide an update on the case at 11:30 a.m. Friday.
If you have any information, you are asked to call the Plainville police at 860-747-1616.
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