Police say a 75-year-old man died of a heart attack after getting into an altercation with a woman over a seat on a San Francisco bus.

San Francisco police say they have launched a suspicious death and assault investigation following the Thursday incident.

Officer Giselle Talkoff tells the San Francisco Chronicle (http://bit.ly/1Vg2BVo) the man, whose name was being withheld by the medical examiner's office pending notification of his relatives, died while on a Muni bus at Kearny at Geary streets.

She says the man went into cardiac arrest and died just moments after getting into an argument with a 53-year-old woman over a seat on another bus.

Talkoff says the incident remains under investigation and no arrests have been made.