A man died early Sunday morning after being hit by a Muni train between Bayshore Boulevard and Sunnydale Avenue in San Francisco, police say.

Police officers and fire department medics responded to the incident at 1:32 a.m. The man had reportedly been sitting on the couplers between two light rail vehicles while the train was at a stop. As it lurched into motion again, he fell underneath and was fatally struck by the second car.

The man was declared dead at the scene.

This is an ongoing investigation and the cause of death has yet to be determined.

Amanda Bartlett is an SFGATE associate digital reporter. Email: amanda.bartlett@sfgate.com | Twitter: @byabartlett