In a tragic incident in San Antonio, Texas, a 21-year-old man opened fire at a landscape supply company, killing three colleagues before taking his own life, authorities announced on Sunday.

The San Antonio Police Department reported that the victims of the Saturday morning shooting, which took place on the north side of the city, included two men and a woman.

According to KSAT-TV, the sound of gunfire around 8 a.m. caused other employees to flee the scene in panic.