Very tragic news out of New York City this Saturday afternoon: 2 NYPD police officers 'assassinated'; shooter dead: New York (CNN) -- Officer Rafael Ramos sat in the driver's seat. Officer Wenjian Liu was at his side. The two cops weren't at their usual precinct -- normally, the pair was assigned to downtown Brooklyn, but they were working a "critical response" detail in an area with higher crime, police said. That's where they were slain, ambush-style -- Saturday afternoon as they sat in their patrol car, New York Police Commissioner William Bratton said at an evening news conference. The gunman approached the passenger side of the patrol car and took a shooting stance, witnesses told police.