Zelienople Police Chief Jim Miller said the teens were volunteer town firefighters whose parents reported them missing early Wednesday, Pittsburgh's WTAE-TV reported Wednesday.
A search for the two 18-year-olds and one 17-year-old led to the discovery of their vehicle in a lake on the border of Beaver and Butler counties.
Authorities said it appeared the SUV's driver lost control on ice and rocks, causing the vehicle to clip a tree and plunge into the lake.
"Where the vehicle ended up, it was only about 5 foot of water. Apparently, the vehicle entered the water front-end first, and when the vehicle flipped over, it was on its roof. Apparently, they were trapped inside," Miller told WTAE of Tuesday night's accident.
Two of the victims were identified as Seneca Valley High School seniors Sam Bucci and Elijah Lunsford. The identity of the third victim was not released.