The latest in a spate of gang-related shootings left an 18-year-old San Francisco man dead Tuesday night.

Police said they found Maurice Williamson near Cashmere Street and Dedman Court about 7:45 p.m. He had a gunshot wound to the head.

The shooting is believed to be a gang killing, Police Department spokesman Lt. Troy Dangerfield said. No arrests have been made, and police are asking for the public’s help.

Police also suspect gangs are responsible for a killing Dec. 16 in a housing development in the Potrero Hill neighborhood.

The victim in that case, identified by the Medical Examiner’s Office as Grady Anderson, 17, was shot about 7:20 p.m. in the 1600 block of 25th Street.

That shooting was the second in two days in the area. On Dec. 14, a 20-year-old man was shot while parking his car on 26th Street near Connecticut Street about 9:45 p.m. The man survived the shooting, which police said was gang-related.

And on Halloween, a 3-year-old girl and her grandfather were caught in the crossfire of another gang-involved shooting in the same Potrero Hill complex, according to police. The intended target, a 20-year-old, was struck but survived.

The latest homicide is the 49th of the year in The City.

bbegin@sfexaminer.com