The explosion happened in the pre-dawn hours at the Dali nightclub in the province of Trujillo along Peru's northern coast, according to a statement from the local Emergency Operations Centre.
It is a region that has recently been plagued by violence and crime.
It was not immediately clear who was responsible and a motive was not immediately known.
At least five of the injured were in serious condition, according to Trujillo Health Network executive director Gerardo Florián Gómez.
Some of the victims suffered amputations and shrapnel wounds and were undergoing surgery, he told reporters.
Among the injured are three minors: one 16-year-old and two 17-year-olds, Florián said.
Fiorella Mantilla, who was at the nightclub when the blast took place, told reporters that she had glass embedded in her legs and recalled that "it sounded as if the sound system had suddenly been turned off".
In a video published by local newspaper La República, some people in the club yelled "Bomb!" and then, "Let's go!" following the explosion.
A person who filmed the scene then focused on a woman lying on the floor and said, "Help the girl!".
The explosion took place less than a month after another blast in the same city that damaged 25 homes but caused no injuries or fatalities.
Extortion and illegal mining plague the La Libertad region, whose Andean portion is home to the largest gold-producing area in Peru.
In 2025, the region experienced 286 explosions, 136 of which occurred in the city of Trujillo, according to official figures.
The expansion of organised criminal groups has led to an increase in related crimes such as extortion.
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