After dragging 46 bodies from the streets near his hometown on the Syrian coast, Omar lost count. For four days, he said, he could not eat, remembering the burned body of a baby just a few months old; a fetus ripped from a woman’s belly; a friend lying dead, his dog still standing guard.

Omar survived what residents, antigovernment activists and human rights monitors are calling one of the darkest recent episodes in the Syrian war, a massacre in government-held Tartus Province that has inflamed sectarian divisions, revealed new depths of depravity and made the prospect of stitching the country back together appear increasingly difficult.

That mass killing this month was one in a series of recent sectarian-tinged attacks that Syrians on both sides have seized on to demonize each other. Government and rebel fighters have filmed themselves committing atrocities for the world to see.

Footage routinely shows pro-government fighters beating, killing and mutilating Sunni rebel detainees, forcing them to refer to President Bashar al-Assad as God. One rebel commander recently filmed himself cutting out an organ of a dead pro-government fighter, biting it and promising the same fate to Alawites, members of Mr. Assad’s Shiite Muslim sect.

That lurid violence has fueled pessimism about international efforts to end the fighting. As the United States and Russia work to organize peace talks next month between Mr. Assad and his opponents, the ever more extreme carnage makes reconciliation seem more remote.

Nadim Houry, the director of Human Rights Watch in Beirut, said he sensed “a complete disconnect between diplomacy and events on the ground.”

“The conflict is getting more visceral,” he said. Without concrete confidence-building measures, he said, and with more people “seeing it as an existential struggle, it’s hard to imagine what the negotiations would look like.”

Attorney General Eric H. Holder Jr. said on Tuesday that he had ordered the Justice Department and the F.B.I. to open an investigation into whether Internal Revenue Service officials broke any criminal laws by singling out conservative groups for special scrutiny.

The activities of I.R.S. officials are already the subject of an investigation by the agency’s inspector general. The results of that inquiry, which are expected in the next several days, are likely to detail how officials at the agency selected political groups for extra scrutiny about their tax status.

Speaking at a news conference called on Tuesday to discuss Medicare fraud, Mr. Holder said that he had ordered a second investigation to determine whether any criminal laws may have been broken by the officials at the tax collection agency.

The attorney general said there were “a variety of statutes within the I.R.S. code” that could be the basis of a criminal violation. He said officials conducting the investigation would also look at “other things in Title 18” of the United States Code. Title 18 is the overall criminal code for the federal government.

Mr. Holder also fielded questions about the seizure of telephone records from reporters and editors at The Associated Press, which apparently came in connection with an investigation of leaks inside the executive branch.

Mr. Holder said that he had recused himself last year from the leak investigation and therefore had not made the decision to seek sweeping subpoenas for two months of call records for 20 telephone lines used by The A.P. and its journalists. He said he decided to turn over supervision of leak inquiries to his deputy, James M. Cole, “to make sure that this investigation was seen as independent” after F.B.I. agents interviewed him about leaks in June 2012.

But Mr. Holder said that the leak in question — the revelation by The A.P. of a foiled terrorist plot by Al Qaeda’s branch in Yemen a year ago — was among the two or three most serious leaks he had seen since the 1970s. “It put the American people at risk,” he said, without elaborating.

A Mother’s Day second-line shooting on Frenchmen Street in the 7th Ward, on Sunday about 1:45 p.m., left 19 people injured, according to the latest NOPD numbers. Earlier Sunday afternoon, NOPD Superintendent Ronal Serpas said that about 12 people had been injured, but the toll later grew to 19, with the NOPD explaining that some victims initially hadn’t reported being injured and more people continue to come forward.

Police said 10 adult men, seven adult women, a 10-year-old boy and a 10-year-old girl were struck by bullets. Both of the 10-year-old victims had graze wounds to the body and were in good condition. A man and a woman were reported to be in surgery Sunday evening.

The shooting occurred in the 1400 block of Frenchmen Street at the intersection of North Villere Street. Immediately after the shooting police reported seeing three suspects running from the scene. One suspect was seen running on Frenchman toward North Claiborne, police said.

NOPD spokeswoman Remi Braden said many of the victims were grazed, some by bullets that ricocheted. “At this point, there are no fatalities, and most of the wounds are not life-threatening,” she said in an email.

“But all medical conditions are not known at this time as victims were rushed to nearby hospitals,” Braden continued. “Detectives are conducting interviews, retrieving any surveillance video in the area and, of course, collecting all evidence. This is an extremely unusual occurrence, and we’re confident that we will make swift arrests.”

A shudder went through Wall Street on Friday after the revelation that Bloomberg News reporters had extracted subscribers’ private information through the company’s ubiquitous data terminals to break news.

The company confirmed that reporters at Bloomberg News, the journalism arm of Bloomberg L.P., had for years used the company’s terminals to monitor when subscribers had logged onto the service and to find out what types of functions, like the news wire, corporate bond trades or an equities index, they had looked at. Bloomberg terminals, which cost an average of more than $20,000 a year, are found in nearly every banking and trading company.

Bloomberg said the functions that allowed journalists to monitor subscribers were a mistake and were promptly disabled after Goldman Sachs complained that a Bloomberg reporter had, while inquiring about a partner’s employment status, pointed out that the partner had not logged onto his Bloomberg terminal lately.

The incident led to broader concerns about the line at Bloomberg between its lucrative terminal business and the hypercompetitive newsroom, threatening to undermine the credibility of both. In a secretive world that thrives on opacity, traders and financial firms jealously guard every speck of information about their activity to avoid tipping their hand on their trades and investments.

“On Wall Street, anonymity is critically important. Secrecy and the ability to cover one’s tracks is paramount,” said Michael J. Driscoll, a former senior trader at Bear Stearns who now teaches at Adelphi University. He added: “If Bloomberg reporters crossed that line, that’s an issue.”

The news gathering technique appears more widespread than the Goldman incident, which was first reported by The New York Post. A preliminary analysis at Bloomberg revealed that “several hundred” reporters had used the technique, a person briefed on the analysis said. (Bloomberg employs more than 2,400 journalists worldwide. A spokesman declined to comment on the analysis and said no reporters had been fired.)