Vancouver police arrested a man Sunday after two unprovoked assaults in the downtown core, thanks in part to quick action from members of the public.Around 11:30 a.m., a 40-year-old man was walking near Granville and West Pender St. when a stranger allegedly approached and shoved him several times before walking off. Moments later, the same suspect allegedly targeted a couple on Granville St., violently throwing one of them to the ground before fleeing on foot..Witnesses chased the man to a nearby lane and held him until police arrived minutes later.The victim, a 30-year-old woman visiting from Germany, was treated in hospital for minor physical injuries.Daniel James Johnny, 29, has been charged with assault by choking and two counts of assault.He remains in custody.