Police in Florida say a bus driver fatally shot two passengers over the weekend. The Miami-Dade Transit driver opened fire on two men who were riding the bus just before 3 a.m. on Sunday morning.

The driver was arrested and questioned but has not yet been charged. An investigation is ongoing.

The shooting took place at around 3 a.m. Sunday as the two men were riding the bus in Miami Gardens, according to the city’s police department.

Miami-Dade bus drivers are not allowed to be armed while on the job, according to Deborah Souverain, a spokesperson for the county’s Transportation and Public Works Department.