Gen. George W. Casey Jr., the senior American commander in Iraq, said Wednesday that “terrorists and death squads” were responsible for the surge in sectarian killings here in recent weeks, and that there might be a need to move more American forces into the capital to prevent the deadly cycle from worsening. His remarks came on a day when at least 30 people were killed and 37 wounded in and around Baghdad, including 20 people who were kidnapped from a bus station 60 miles north of the city and killed, Iraqi officials said. A local police official offered a slightly different account of that episode. Full Story