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 man was shot to the chest on Fenton Avenue at 12:40 a.m.

He died at Jacobi Hospital, sources 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. The 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.

This is the second deadly shootout to take place in the Bronx in a week. Last Friday night and early Saturday morning, 13 people were shot in eight incidents, including two teenagers, who were killed.