After a violent weekend in which seven people died and 26 were wounded by gunfire, the city is stepping up not only patrols but surveillance with its fleet of Terrahawk vans and Skywatch towers. If you haven’t seen these things in action, they’re basically camera-equipped observation decks on scissor lifts. The Terrahawks are the mobile version of the Skywatch, the NYPD explains on its Facebook page. The department also plans to assign more uniformed and plainclothes officers to housing developments “during the shooting-prone hours,” as the department increases its enforcement of open warrants and investigators monitor crews for signs of retaliation. Meanwhile, the 11-year-old girl paralyzed by a stray bullet moved her arms on Monday, and the suspect in a triple shooting in Brooklyn has been charged with attempted murder. City officials say the weekend’s violence was an exception, but at least they’re taking it seriously.