SAN FRANCISCO -- Police in San Francisco took in 187 weapons during a gun buy-back Saturday morning.The four-hour event, hosted by United Playaz, yielded 57 pistols, 44 revolvers, 11 assault weapons and three shotguns. One of those shotguns was homemade.United Playaz is a violence prevention and youth development organization located on Howard Street in San Francisco's South of Market district.The event offered $100 for every handgun and $200 for every assault weapon, no questions asked.Police were pleased by the results and said that they were kept busy. The event was the seventh such buy-back, said David Stevenson, San Francisco police director of communications."We don't know what to expect year to year," Stevenson said."Even getting one gun off the street is a good thing if it measured by its potential for harm."