Mayhem erupted in The Bronx and Upper Manhattan early this morning as seven people were shot — including one who was killed — in five incidents in less than an hour, authorities said.

In the most serious case in The Bronx, a 16-year-old male was shot in the torso while playing in a yard at 3482 Fenton Avenue in Williamsbridge at about 12:40 a.m. He died at Jacobi Hospital, sources said. A police officer believes he was hit by a stray bullet in a “drive-by” shooting. The boy was visiting from Connecticut with his father, who had gone to run errands, a neighbor said.

Just 20 minutes later, three people were shot on Hull Avenue, near Gun Hill Road. Their injuries were not considered life-threatening.

Also at 1 a.m., one man was shot in the leg at 234th Street and Broadway. He is in stable condition.

A short time later, another man was shot at Andrews Avenue South and West Burnside Avenue. His injuries were not serious.

The wave of violence started at 12:35 a.m. when a man was shot in the leg at 132nd Street and Lenox Avenue, in Harlem. His injuries were not considered life-threatening.