The limousine accident in Schoharie, N.Y., on Saturday took 20 lives almost instantly. It devastated families, killing siblings and leaving young children without parents. The victims were friends and relatives — including four sisters from one family, and two brothers from another — who were traveling to a brewery in Cooperstown, N.Y., to celebrate a 30th birthday.

Instead, they were killed when the oversized limousine they were traveling in barreled through an intersection that is known locally for its danger and crashed into an unoccupied car — and two other people, killing them — before coming to a rest in a shallow ravine.

Investigators have said little about what they know about the accident, believed by federal officials to be the deadliest transportation incident since a 2009 air crash. But details about the victims are beginning to emerge.