WASHINGTON — The swearing-in of Barack Obama came off without a security-related hitch Tuesday, but underneath the calm veneer, federal authorities were intensively investigating a report that a group of Somalia-based militants wanted to launch some kind of inauguration-related attack.
Secret Service officials anxiously oversaw what was by far the largest-ever security operation for a presidential inauguration, marshaling the forces of several dozen federal, state and local law enforcement and intelligence agencies.
Their biggest white-knuckle moment: when the new president and First Lady Michelle Obama exited their heavily fortified limousine and walked along long stretches of Pennsylvania Avenue on their way from the Capitol to the White House.
As they strolled, government counter-snipers patrolled rooftops and hyper-alert Secret Service agents fanned out around the couple, scouring parade viewers often more than a dozen deep for the glint of a handgun or some other kind of weapon.
The biggest concern was whether the crowds would get unruly.
"The crowd has been well-behaved. No problems," said Sgt. Ernesto Celaya of the San Antonio Police Department as he and 60 of his brown-uniformed men and women faced the crowd along one portion of the parade route.
The day's responsibilities ended for most security officers at 4:39 p.m., when the Obamas entered the White House. But for others, work will continue as authorities search for any indication that the Somalia-based threat was real.
Russ Knocke, chief spokesman for the Department of Homeland Security, said authorities were taking the threat seriously, but that it was "of limited specificity and uncertain credibility."
Knocke said the FBI, the Secret Service and other Department of Homeland Security agencies, and the intelligence community were investigating and analyzing recently received information "about a potential threat on Inauguration Day."
"Authorities at all levels are vigorously pursuing any lead relating to this threat information," Knocke said of the intelligence bulletin that first went out to local, state and federal agencies Monday night. The Obama "transition team has been briefed and is fully integrated into the process."
One federal law enforcement official said the threat involved individuals affiliated with Shabab, an Islamist extremist group that is active in Somalia. In recent years, authorities have become concerned that U.S.-based Somalis are traveling to Somalia to fight with Shabab and other extremists there against U.S. ally Ethiopia.
The threat information came from an individual overseas whose credibility has not been established, and indicated that extremists "might attempt to travel to the United States in an attempt to do something in the inauguration time period," said the law enforcement official, who spoke on the condition of anonymity because of the classified nature of the information.
The official said the threat did not specify Washington and could apply to inauguration-related festivities around the country, and that there was no indication that anyone connected with the threat has even tried to enter the United States.
Times staff writer Faye Fiore and Tom Hamburger and David Wood in our Washington bureau contributed to this report.