A student livestreamed his attack on a junior high school in the southern Philippines on Tuesday that left one schoolmate dead, the authorities said.

The gunman shot and killed a male schoolmate before fatally turning the gun on himself, Mayor Khymer Olaso of Zamboanga City said in an interview with a local radio station on Tuesday morning.

The boy was armed with a “high-powered firearm” and a .45-caliber pistol, and livestreamed the shooting on social media, Mr. Olaso said.

The shooting took place around 8 a.m. local time at the junior high school of Ateneo de Zamboanga University. The junior high school is a separate location from the university’s main campus in Zamboanga City on the southern island of Mindanao.

The student who was identified by the authorities as the gunman, as well as the victim, were both minors, the police said. Mr. Olaso said an investigation was underway.

Rev. Guillrey Anthony Andal, the president of Ateneo de Zamboanga University, said in a news briefing that all other students had been evacuated safely. He said that classes at all levels of the university were suspended on Tuesday, including at an elementary school on the same campus as the junior high.

The shooting in Zamboanga City came less than two months after two teenagers killed three people and wounded seven others after opening fire at their high school in Tacloban, a city in the central Philippines. The boys were arrested, and the police said the motive appeared to be a grudge over bullying.

This is a developing story.

Jason Gutierrez contributed reporting.